fm10k/base: improve comments

fm10k/base: improve comments

The comment for fm10k_iov_msg_lport_state_pf was changed during
review of kernel driver, and the new wording is slightly clearer.
Re-write the comment in base code based on this new wording.

Fix a number of mailbox comment issues with function header comments,
lower-case acronyms (i.e. FIFO, TLV), incorrect function names in
DEBUGFUNC(), duplicate comments and a stubbed-out header comment for
fm10k_sm_mbx_init.

Signed-off-by: Wang Xiao W <xiao.w.wang@intel.com>
Tested-by: Heng Ding <hengx.ding@intel.com>
Acked-by: Jing Chen <jing.d.chen@intel.com>