bnxt: fix intermittent VLAN issues

bnxt_init() is invokes Function Reset (bnxt_hwrm_func_reset) and thus FW
configuration for VLANs get erased. To fix this, in bnxt_init(), Invoking
HWRM to configure VLANs (bnxt_hwrm_cfa_l2_set_rx_mask).

Submitted by: Siva Kallam <siva.kallam@@broadcom.com>
Reviewed by: shurd, sbruno
Approved by: sbruno (mentor)
Sponsored by: Broadcom Limited
Differential Revision: https://reviews.freebsd.org/D12527