alpha: Use absolute_pointer to define COMMAND_LINE

alpha:allmodconfig fails to build with the following error
when using gcc 11.x.

  arch/alpha/kernel/setup.c: In function 'setup_arch':
  arch/alpha/kernel/setup.c:493:13: error:
	'strcmp' reading 1 or more bytes from a region of size 0

Avoid the problem by declaring COMMAND_LINE as absolute_pointer().
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/alpha/include/asm/setup.h

@@ -36,7 +36,7 @@
  * place.
  */
 #define PARAM			ZERO_PGE
-#define COMMAND_LINE		((char *)(PARAM + 0x0000))
+#define COMMAND_LINE		((char *)(absolute_pointer(PARAM + 0x0000)))
 #define INITRD_START		(*(unsigned long *) (PARAM+0x100))
 #define INITRD_SIZE		(*(unsigned long *) (PARAM+0x108))