[media] img-ir: fix sparse warnings

drivers/media/rc/img-ir/img-ir-nec.c:111:23: warning: symbol 'img_ir_nec' was not declared. Should it be static?
drivers/media/rc/img-ir/img-ir-jvc.c:54:23: warning: symbol 'img_ir_jvc' was not declared. Should it be static?
drivers/media/rc/img-ir/img-ir-sony.c:120:23: warning: symbol 'img_ir_sony' was not declared. Should it be static?
drivers/media/rc/img-ir/img-ir-sharp.c:75:23: warning: symbol 'img_ir_sharp' was not declared. Should it be static?
drivers/media/rc/img-ir/img-ir-sanyo.c:82:23: warning: symbol 'img_ir_sanyo' was not declared. Should it be static?

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>