arch-ppc.h: Fix typo in header guard

Signed-off-by: Akash Verma <akashv@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/arch/arch-ppc.h b/arch/arch-ppc.h
index 6c1029c..8313331 100644
--- a/arch/arch-ppc.h
+++ b/arch/arch-ppc.h
@@ -1,5 +1,5 @@
 #ifndef ARCH_PPC_H
-#define ARCH_PPH_H
+#define ARCH_PPC_H
 
 #include <unistd.h>
 #include <stdlib.h>