bnxt_en: alloc tc_info{} struct only when tc flower is enabled

TC flower is not enabled on VFs and when there's no FW support.
Alloc the tc_info{} struct at init time only when TC flower is being
enabled.

Signed-off-by: Sathya Perla <sathya.perla@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>