tool: Move ALIGN_MASK to header as common MACRO

The ALIGN code is need by many files who need handle structure or image
align, so move the macro to imagetool.h file.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Punit Agrawal <punit1.agrawal@toshiba.co.jp>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/tools/imagetool.h b/tools/imagetool.h
index e1c778b..81e5cd0 100644
--- a/tools/imagetool.h
+++ b/tools/imagetool.h
@@ -25,6 +25,9 @@
 
 #define ARRAY_SIZE(x)		(sizeof(x) / sizeof((x)[0]))
 
+#define __ALIGN_MASK(x, mask)	(((x) + (mask)) & ~(mask))
+#define ALIGN(x, a)		__ALIGN_MASK((x), (typeof(x))(a) - 1)
+
 #define IH_ARCH_DEFAULT		IH_ARCH_INVALID
 
 /* Information about a file that needs to be placed into the FIT */