media: v4l2-subdev: Fix alloc failure check in v4l2_subdev_call_state_try()

v4l2_subdev_call_state_try() macro allocates a subdev state with
__v4l2_subdev_state_alloc(), but does not check the returned value. If
__v4l2_subdev_state_alloc fails, it returns an ERR_PTR, and that would
cause v4l2_subdev_call_state_try() to crash.

Add proper error handling to v4l2_subdev_call_state_try().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Fixes: 982c0487 ("media: subdev: Add v4l2_subdev_call_state_try() macro")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/aJTNtpDUbTz7eyJc%40stanley.mountain/


Cc: stable@vger.kernel.org
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>