[consutil] show command will crash if there are no ttyUSB device under \dev

[Blueve]

Description

consutil show command will crash if there are no ttyUSB device under \dev

Steps to reproduce the issue

1. run consutil show on a DUT without any ttyUSB device

Describe the results you received

Command resulted in error: ls: cannot access '/dev/ttyUSB*': No such file or directory

Describe the results you expected

A console line table.

Additional information you deem important (e.g. issue happens only occasionally)

Output of show version

SONiC Software Version: SONiC.master.443-bba5df05
Distribution: Debian 10.6
Kernel: 4.19.0-9-2-amd64
Build commit: bba5df05
Build date: Tue Oct 13 19:50:56 UTC 2020
Built by: johnar@jenkins-worker-11

Platform: x86_64-cel_e1031-r0
HwSKU: Celestica-E1031-T48S4
ASIC: broadcom
/usr/local/bin/decode-syseeprom : ERROR : Failed to read eeprom : [Errno 2] No such file or directory: '/sys/class/i2c-adapter/i2c-2/2-0050/eeprom'
Serial Number: 
Uptime: 11:27:46 up  1:15,  1 user,  load average: 0.53, 1.47, 1.61

Docker images:
REPOSITORY                    TAG                   IMAGE ID            SIZE
docker-teamd                  latest                bd1df6fe3cbc        394MB
docker-teamd                  master.443-bba5df05   bd1df6fe3cbc        394MB
docker-nat                    latest                2db062aaf7f7        396MB
docker-nat                    master.443-bba5df05   2db062aaf7f7        396MB
docker-router-advertiser      latest                44f82f06d9e3        359MB
docker-router-advertiser      master.443-bba5df05   44f82f06d9e3        359MB
docker-platform-monitor       latest                4c51bd437497        441MB
docker-platform-monitor       master.443-bba5df05   4c51bd437497        441MB
docker-lldp                   latest                ea22f55f7cff        388MB
docker-lldp                   master.443-bba5df05   ea22f55f7cff        388MB
docker-database               latest                a87c7ce0bda1        359MB
docker-database               master.443-bba5df05   a87c7ce0bda1        359MB
docker-orchagent              latest                9ed19e1a8b00        407MB
docker-orchagent              master.443-bba5df05   9ed19e1a8b00        407MB
docker-dhcp-relay             latest                7d5aaaeacf8c        366MB
docker-dhcp-relay             master.443-bba5df05   7d5aaaeacf8c        366MB
docker-sonic-telemetry        latest                a8c51245a513        429MB
docker-sonic-telemetry        master.443-bba5df05   a8c51245a513        429MB
docker-sonic-mgmt-framework   latest                cab64d10b3ac        486MB
docker-sonic-mgmt-framework   master.443-bba5df05   cab64d10b3ac        486MB
docker-sflow                  latest                ee01daa4595c        397MB
docker-sflow                  master.443-bba5df05   ee01daa4595c        397MB
docker-fpm-frr                latest                a9df2f6c4db5        410MB
docker-fpm-frr                master.443-bba5df05   a9df2f6c4db5        410MB
docker-snmp                   latest                2ffc7ed302ef        399MB
docker-snmp                   master.443-bba5df05   2ffc7ed302ef        399MB
docker-syncd-brcm             latest                b826fbfdc0c0        542MB
docker-syncd-brcm             master.443-bba5df05   b826fbfdc0c0        542MB