Support CMSIS_device_header macro provided in CMSIS

This patch creates the tfm_hal_device_header.h to make the device header
in TF-M compliant with CMSIS.
CMSIS uses a preprocessor define CMSIS_device_header that reflects the
actual device name.
With this patch, if the CMSIS_device_header is defined, then the device
header defined by the macro will be included, otherwise the original
cmsis.h.
To be noted that the existing platform ports are not affected.

Change-Id: If24337be37188335ea514769fd90de75365925d9
Signed-off-by: Kevin Peng <kevin.peng@arm.com>
diff --git a/bl2/ext/mcuboot/bl2_main.c b/bl2/ext/mcuboot/bl2_main.c
index 081d88f..6ff4197 100644
--- a/bl2/ext/mcuboot/bl2_main.c
+++ b/bl2/ext/mcuboot/bl2_main.c
@@ -18,7 +18,7 @@
 #include <assert.h>
 #include "bl2_util.h"
 #include "target.h"
-#include "cmsis.h"
+#include "tfm_hal_device_header.h"
 #include "Driver_Flash.h"
 #include "mbedtls/memory_buffer_alloc.h"
 #include "bootutil/bootutil_log.h"