[PATCH v2] powerpc/mm/radix: use do/while(0) trick for single statement block

[Mathieu Malaterre]

In commit 7a22d6321c3d ("powerpc/mm/radix: Update command line parsing for
disable_radix") an `if` statement was added for a possible empty body
(prom_debug).

Fix the following warning, treated as error with W=1:

  arch/powerpc/kernel/prom_init.c:656:46: error: suggest braces around empty body in an ‘if’ statement [-Werror=empty-body]

Suggested-by: Randy Dunlap <rdunlap at infradead.org>
Signed-off-by: Mathieu Malaterre <malat at debian.org>
---
v2: update macro directly

 arch/powerpc/kernel/prom_init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 5ae153b97d0a..7edf3aa5bc6d 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -103,7 +103,7 @@ int of_workarounds;
 #ifdef DEBUG_PROM
 #define prom_debug(x...)	prom_printf(x)
 #else
-#define prom_debug(x...)
+#define prom_debug(x...)	do { } while (0)
 #endif
 
 
-- 
2.11.0