V4L/DVB: IR/imon: minor change_protocol fixups

This is a follow-up to my prior patch implementing ir-core's
change_protocol functionality in the imon driver, which eliminates
a false warning when change_protocol is called without a specific
protocol selected yet (i.e., still IR_TYPE_UNKNOWN). It also removes
some extraneous blank lines getting spewn into dmesg.

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