bnxt_en: Fix DCB ETS validation

bnxt_en: Fix DCB ETS validation

In bnxt_ets_validate(), the code incorrectly loops over all possible
traffic classes to check and add the ETS settings.  Fix it to loop
over the configured traffic classes only.

The unconfigured traffic classes will default to TSA_ETS with 0
bandwidth.  Looping over these unconfigured traffic classes may
cause the validation to fail and trigger this error message:

"rejecting ETS config starving a TC\n"

The .ieee_setets() will then fail.

Fixes: 7df4ae9fe855 ("bnxt_en: Implement DCBNL to support host-based DCBX.")
Reviewed-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Signed-off-by: Shravya KN <shravya.k-n@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20250710213938.1959625-2-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>