common: image.c: Fix CACHE: Misaligned operation output

When booting a itb file with a Ramdisk on a imx6 based
board, U-Boot drops the warning:

Loading Kernel Image ... OK
Loading Ramdisk to 4ecf1000, end 4ef8b11f ... \
CACHE: Misaligned operation at range [4ecf1000,  4ef8b11f]

Fix it!

Signed-off-by: Heiko Schocher <hs@denx.de>
Tested-by: Ayoub Zaki <hs@denx.de>

common/image.c

@@ -1186,7 +1186,8 @@ int boot_ramdisk_high(struct lmb *lmb, ulong rd_data, ulong rd_len,
 			 * AMP boot scenarios in which we might not be
 			 * HW cache coherent
 			 */
-			flush_cache((unsigned long)*initrd_start, rd_len);
+			flush_cache((unsigned long)*initrd_start,
+				    ALIGN(rd_len, ARCH_DMA_MINALIGN));
 #endif
 			puts("OK\n");
 		}