media: rc: make scancodes 64 bit

There are many protocols that encode more than 32 bit. We want 64 bit
support so that BPF IR decoders can decode more than 32 bit. None of
the existing kernel IR decoders/encoders support 64 bit, for now.

The MSC_SCAN event can only contain 32 bit scancodes, so we only generate
MSC_SCAN events if the scancode fits into 32 bits. The full 64 bit
scancode can be read from the lirc chardev.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>