Copy these macros from ia64/include/asm/agp.h to avoid the
"empty-body" in 'if' statment warning.

drivers/char/agp/generic.c: In function 'agp_generic_destroy_page':
../drivers/char/agp/generic.c:1265:42: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
 1265 |                 unmap_page_from_agp(page);

Signed-off-by: Randy Dunlap <redacted>
Cc: Richard Henderson <redacted>
Cc: Ivan Kokshaysky <redacted>
Cc: Matt Turner <mattst88@gmail.com>
Cc: linux-alpha@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Airlie <redacted>
---
 arch/alpha/include/asm/agp.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- linux-next-20210806.orig/arch/alpha/include/asm/agp.h
+++ linux-next-20210806/arch/alpha/include/asm/agp.h

@@ -6,8 +6,8 @@
 
 /* dummy for now */
 
-#define map_page_into_agp(page) 
-#define unmap_page_from_agp(page) 
+#define map_page_into_agp(page)		do { } while (0)
+#define unmap_page_from_agp(page)	do { } while (0)
 #define flush_agp_cache() mb()
 
 /* GATT allocation. Returns/accepts GATT kernel virtual address. */