linux/kernel.h: add typechecking to roundup macro

This commit replaces roundup macro with the one from Linux Kernel.

DEFINE_ALIGN_BUFFER must be fixed because typechecking can not
be used in this context.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
diff --git a/include/common.h b/include/common.h
index c1bdaec..ce0a734 100644
--- a/include/common.h
+++ b/include/common.h
@@ -967,7 +967,7 @@
  * Usage of this macro shall be avoided or used with extreme care!
  */
 #define DEFINE_ALIGN_BUFFER(type, name, size, align)			\
-	static char __##name[roundup(size * sizeof(type), align)]	\
+	static char __##name[ALIGN(size * sizeof(type), align)]	\
 			__aligned(align);				\
 									\
 	static type *name = (type *)__##name