media: allegro: ignore interrupt if mailbox is not initialized

media: allegro: ignore interrupt if mailbox is not initialized

BugLink: https://bugs.launchpad.net/bugs/1951822
[ Upstream commit 1ecda6393db4be44aba27a243e648dc98c9b92e3 ]

The mailbox is initialized after the interrupt handler is installed. As
the firmware is loaded and started even later, it should not happen that
the interrupt occurs without the mailbox being initialized.

As the Linux Driver Verification project (linuxtesting.org) keeps
reporting this as an error, add a check to ignore interrupts before the
mailbox is initialized to fix this potential null pointer dereference.

Reported-by: Yuri Savinykh <s02190703@gse.cs.msu.ru>
Reported-by: Nadezda Lutovinova <lutovinova@ispras.ru>
Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>