net/bnxt: fix setting primary MAC address

net/bnxt: fix setting primary MAC address

1. Default filter is tied to VNIC 0 at index 0. After finding the filter
   with mac_index 0 and set the new MAC address, looping through
   remaining filters is unnecessary.
2. Added a check for NULL MAC address.
3. bnxt_hwrm_set_l2_filter() clears the existing filter configuration
   first before applying new filter settings. Hence there is no need to
   invoke bnxt_hwrm_clear_l2_filter() explicitly in
   bnxt_set_default_mac_addr_op().

Fixes: d69851df12b2 ("net/bnxt: support multicast filter and set MAC addr")
Cc: stable@dpdk.org
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>