[media] tm6000: Fix a warning at tm6000_ir_int_start()

drivers/media/video/tm6000/tm6000-input.c: In function ‘tm6000_ir_int_start’:
drivers/media/video/tm6000/tm6000-input.c:381:3: warning: ‘return’ with no value, in function returning non-void [-Wreturn-type]

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>