[media] Fix RC5 decoding with Fintek CIR chipset

Fix RC5 decoding with Fintek CIR chipset

Commit e87b540b tightened up the RC5
decoding by adding a check for trailing silence to ensure a valid RC5
command had been received. Unfortunately the trailer length checked was
10 units and the Fintek CIR device does not want to provide details of a
space longer than 6350us. This meant that RC5 remotes working on a
Fintek setup on 3.16 failed on 3.17 and later. Fix this by shortening
the trailer check to 6 units (allowing for a previous space in the
received remote command).

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=117221



Signed-off-by: Jonathan McDowell <noodles@earth.li>
Cc: stable@vger.kernel.org
Signed-off-by: David Härdeman <david@hardeman.nu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>