media: siano: Simplify smscore_load_firmware_from_file

The function is never called with a loadfirmware_handler, so we can
remove some dead code.

We can also use this as a excuse to remove some unused type definitions.

This fixes the following smatch warning:
drivers/media/common/siano/smscoreapi.c:1172 smscore_load_firmware_from_file() error: we previously assumed 'loadfirmware_handler' could be null (see line 1150)

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reported-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Closes: https://lore.kernel.org/linux-media/99bd75a0-a6f3-4c47-bc89-70ffd87da756@xs4all.nl/T/#t


Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>