RDMA/bnxt_re: handle command completions after driver detect a timedout

If calling context detect command timeout, associated memory stored on
stack will not be valid. If firmware complete the same command later,
this causes incorrect memory access by driver.

Added is_waiter_alive to handle delayed completion by firmware.
is_waiter_alive is set and reset under command queue lock.

Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com>
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Link: https://lore.kernel.org/r/1686308514-11996-11-git-send-email-selvin.xavier@broadcom.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>