[media] rc: call input_sync after scancode reports

Due to commit cdda911c, evdev only
becomes readable when the buffer contains an EV_SYN/SYN_REPORT event. If
we get a repeat or a scancode we don't have a mapping for, we never call
input_sync, and thus those events don't get reported in a timely
fashion.

For example, take an mceusb transceiver with a default rc6 keymap. Press
buttons on an rc5 remote while monitoring with ir-keytable, and you'll
see nothing. Now press a button on the rc6 remote matching the keymap.
You'll suddenly get the rc5 key scancodes, the rc6 scancode and the rc6
key spit out all at the same time.

Pressing and holding a button on a remote we do have a keymap for also
works rather unreliably right now, due to repeat events also happening
without a call to input_sync (we bail from ir_do_keydown before getting
to the point where it calls input_sync).

Easy fix though, just add two strategically placed input_sync calls
right after our input_event calls for EV_MSC, and all is well again.
Technically, we probably should have been doing this all along, its just
that it never caused any functional difference until the referenced
change went into the input layer.

input_sync once per IR signal. There was another hidden bug in the code
where we were calling input_report_key using last_keycode instead of our
just discovered keycode, which manifested with the reordering of calling
input_report_key and setting last_keycode.

Reported-by: Stephan Raue <sraue@openelec.tv>
CC: Stephan Raue <sraue@openelec.tv>
CC: Mauro Carvalho Chehab <mchehab@redhat.com>
CC: Jeff Brown <jeffbrown@android.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>