ice: Fix tx queue rate limit when TCs are configured

Configuring tx_maxrate via sysfs interface
/sys/class/net/eth0/queues/tx-1/tx_maxrate was not working when
TCs are configured because always main VSI was being used. Fix by
using correct VSI in ice_set_tx_maxrate when TCs are configured.

Fixes: 1ddef455 ("ice: Add NDO callback to set the maximum per-queue bitrate")
Signed-off-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>
Tested-by: Bharathi Sreenivas <bharathi.sreenivas@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>