[media] Fix sysfs rc protocol lookup for rc-5-sz

With the current matching rules the lookup for rc protocol named rc-5-sz matches with "rc-5" before finding "rc-5-sz". Thus one is able to never enable/disable the rc-5-sz protocol via sysfs.

Fix the lookup to require an exact match which allows the manipulation of sz protocol.

Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>