V4L/DVB: media/IR: nec-decoder needs to select BITREV

Fix ir-nec-decoder build: it uses bitrev library code, so
select BITREVERSE in its Kconfig.

ir-nec-decoder.c:(.text+0x1a2517): undefined reference to `byte_rev_table'
ir-nec-decoder.c:(.text+0x1a2526): undefined reference to `byte_rev_table'
ir-nec-decoder.c:(.text+0x1a2530): undefined reference to `byte_rev_table'
ir-nec-decoder.c:(.text+0x1a2539): undefined reference to `byte_rev_table'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>