bnxt_en: Protect bnxt_set_eee() and bnxt_set_pauseparam() with mutex.

All changes related to bp->link_info require the protection of the
link_lock mutex.  It's not sufficient to rely just on RTNL.

Fixes: 163e9ef6 ("bnxt_en: Fix race when modifying pause settings.")
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>