[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/rc/rc-raw.c b/drivers/media/rc/rc-raw.c
index ab9b1e40..165412f 100644
--- a/drivers/media/rc/rc-raw.c
+++ b/drivers/media/rc/rc-raw.c
@@ -357,7 +357,7 @@
 	load_lirc_codec();
 
 	/* If needed, we may later add some init code. In this case,
-	   it is needed to change the CONFIG_MODULE test at ir-core.h
+	   it is needed to change the CONFIG_MODULE test at rc-core.h
 	 */
 }
 #endif