media: rc-core: improve ir_raw_store_edge() handling

The gpio-ir-recv driver does many wakeups (once per edge); the saa7134
driver has special handling to only wakeup 15ms after the first edge.
Make this part of rc-core so gpio-ir-recv also benefits from
this (so a rc-5 keypress now causes 3 wakeups rather than 24).

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>