[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/include/media/ir-kbd-i2c.h b/include/media/ir-kbd-i2c.h
index d27505f..f22b359 100644
--- a/include/media/ir-kbd-i2c.h
+++ b/include/media/ir-kbd-i2c.h
@@ -1,7 +1,7 @@
 #ifndef _IR_I2C
 #define _IR_I2C
 
-#include <media/ir-core.h>
+#include <media/rc-core.h>
 
 #define DEFAULT_POLLING_INTERVAL	100	/* ms */