rpi3: Move rpi3_hw.h header file to include/rpi_hw.h

With the advent of Raspberry Pi 4 support, we need to separate some
board specific headers between the RPi3 and RPi4.
Rename and move the "rpi3_hw.h" header, so that .c files just include
rpi_hw.h, and automatically get the correct version.

Change-Id: I03b39063028d2bee1429bffccde71dddfe2dcde8
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/plat/rpi/rpi3/include/platform_def.h b/plat/rpi/rpi3/include/platform_def.h
index 4d90222..2a12fe7 100644
--- a/plat/rpi/rpi3/include/platform_def.h
+++ b/plat/rpi/rpi3/include/platform_def.h
@@ -12,7 +12,7 @@
 #include <lib/utils_def.h>
 #include <plat/common/common_def.h>
 
-#include "../rpi3_hw.h"
+#include "rpi_hw.h"
 
 /* Special value used to verify platform parameters from BL2 to BL31 */
 #define RPI3_BL31_PLAT_PARAM_VAL	ULL(0x0F1E2D3C4B5A6978)