powerpc: tiny memcpy_(to|from)io optimisation

This trivial patch changes memcpy_(to|from)io as to transfer as many
32-bit words as possible in 32-bit accesses (in the current solution,
the last 32-bit word was transferred as 4 byte accesses).

Signed-off-by: Albrecht Dreß <albrecht.dress@arcor.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/powerpc/kernel/io.c b/arch/powerpc/kernel/io.c
index 1882bf4..8dc7547 100644
--- a/arch/powerpc/kernel/io.c
+++ b/arch/powerpc/kernel/io.c
@@ -161,7 +161,7 @@
 		dest++;
 		n--;
 	}
-	while(n > 4) {
+	while(n >= 4) {
 		*((u32 *)dest) = *((volatile u32 *)vsrc);
 		eieio();
 		vsrc += 4;
@@ -190,7 +190,7 @@
 		vdest++;
 		n--;
 	}
-	while(n > 4) {
+	while(n >= 4) {
 		*((volatile u32 *)vdest) = *((volatile u32 *)src);
 		src += 4;
 		vdest += 4;