[Mellanox] Update MFT to v4.21.0-100 (#11758)

- Why I did it
To update MFT package to the latest version.

- How I did it
Updated MFT_VERSION & MFT_REVISION in platform/mellanox/mft.mk.

- How to verify it
Build an image and deploy to the switch
Check MFT version by dpkg -l | grep mft
Verify that all the SONiC services up and running
Run regression testing using tests from sonic-mgmt

Signed-off-by: Volodymyr Samotiy <volodymyrs@nvidia.com>

platform/mellanox/mft.mk

@@ -16,8 +16,8 @@
 #
 # Mellanox SAI
 
-MFT_VERSION = 4.20.0
-MFT_REVISION = 34
+MFT_VERSION = 4.21.0
+MFT_REVISION = 100
 
 export MFT_VERSION MFT_REVISION