media: amphion: output firmware error message

Firmware may send the error event with some error message,
and it help locate the firmware error,
so output the error message if it exists

Fixes: 61cbf1c1 ("media: amphion: implement vpu core communication based on mailbox")
Signed-off-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>