[media] ir-rc6-decoder: Support RC6-6A variable length data

This patch to the IR RC6 decoder adds support for variable length
mode-6A frames which can range in size from 8 to 128 bits.  Please refer
to the following link for a detailed explanation or RC6 frames:
http://slydiman.narod.ru/scr/kb/rc6.htm



This change removes the assumption that frames are fixed length
(currently either 24 or 32 data bits) and actually counts the number of
bits until an end of frame marker is seen.

[mchehab@redhat.com: Tested with a RC-6(0) IR - 16 bits]
Tested-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>