bnxt_en: improve VF error messages when PF is unavailable

The current driver design relies on the PF netdev being open in order
to intercept the following HWRM commands from a VF:
    - HWRM_FUNC_VF_CFG
    - HWRM_CFA_L2_FILTER_ALLOC
    - HWRM_PORT_PHY_QCFG (only if FW_CAP_LINK_ADMIN is not supported)

If the PF is closed, then VFs are subjected to rather inscrutable error
messages in response to any configuration requests involving the above
command types. Recent firmware distinguishes this problem case from
other errors by returning HWRM_ERR_CODE_PF_UNAVAILABLE. In most cases,
the appropriate course of action is still to fail, but this can now be
accomplished with the aid of more user informative log messages. For L2
filter allocations that are already asynchronous, an automatic retry
seems more appropriate.

v2: Delete extra newline.

Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>