[media] rc: rename the remaining things to rc_core

The Remote Controller subsystem is meant to be used not only by Infra Red
but also for similar types of Remote Controllers. The core is not specific
to Infra Red. As such, rename:
	- ir-core.h to rc-core.h
	- IR_CORE to RC_CORE
	- namespace inside rc-core.c/rc-core.h

To be consistent with the other changes.

No functional change on this patch.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/video/cx23885/Kconfig b/drivers/media/video/cx23885/Kconfig
index e1367b3..6b4a516 100644
--- a/drivers/media/video/cx23885/Kconfig
+++ b/drivers/media/video/cx23885/Kconfig
@@ -5,7 +5,7 @@
 	select VIDEO_BTCX
 	select VIDEO_TUNER
 	select VIDEO_TVEEPROM
-	depends on IR_CORE
+	depends on RC_CORE
 	select VIDEOBUF_DVB
 	select VIDEOBUF_DMA_SG
 	select VIDEO_CX25840