bnxt_en: use firmware provided max timeout for messages

Some older devices cannot accommodate the 40 seconds timeout
cap for long running commands (such as NVRAM commands) due to
hardware limitations. Allow these devices to request more time for
these long running commands, but print a warning, since the longer
timeout may cause the hung task watchdog to trigger. In the case of a
firmware update operation, this is preferable to failing outright.

v2: Use bp->hwrm_cmd_max_timeout directly without the constants.

Fixes: 881d8353 ("bnxt_en: Add an upper bound for all firmware command timeouts.")
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>