V4L/DVB (12495): em28xx: Don't call em28xx_ir_init when disable_ir is true

We should call em28xx_ir_init(dev) only when disable_ir is true.

Signed-off-by: Shine Liu <shinel@foxmail.com>
Reviewed-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>