media: si2168: drop support for old firmware file name for si2168 B40

media: si2168: drop support for old firmware file name for si2168 B40

The si2168 B40 firmware file name has been changed in or before 2014.
During initialization, the new file name is preferred, but the old file
name is used as a fallback when request_firmware with the new file name
fails. Once reading the old file name has been attempted, only this name
will be used on further firmware loading attempts. During resume,
firmware reading with the new file name can (and likely will) fail even
when it actually exists. So this permanent switch to the fallback
firmware name happens even when not desired.

Any system using a recent kernel version can be expected to have the
firmware under the new name. The major distributions are either using
the dvb firmware collection from LibreELEC, which has the new firmware
file name, or do not package the firmware file but have documentation
pointing towards a manual installation of the firmware file under the
new name. If the firmware is available under the old name, it is
severely outdated. If the switch to the old file name is performed,
further firmware loading will either permanently fail (if it is not
available) or an outdated firmware version will be used.

Drop support for the fallback firmware file name and fail directly if
the firmware is not available under its current name. On following
attempts, the firmware read will then be retried with the correct
current name instead of the old name.

As reasoned above, there should be no negative effects of this change,
while simplifying code (the B40 variant will be handled identical
compared to the other variants of the si2168) and at the same time
fixing possible problems if firmware loading fails on resume.

Link: https://lore.kernel.org/linux-media/20210418161544.58858-1-kernel@tuxforce.de
Signed-off-by: Lukas Middendorf <kernel@tuxforce.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>