bootm: Align cache flush end address correctly

Flushing part of the cache should be done on cache boundaries. Trying to
flush part of a cache line is not supported and the request may be ignored
or print warnings.

Adjust the bootm code to align the end address to prevent this problem.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heiko Schocher <hs@denx.de>
Tested-on: smartweb, corvus, taurus, axm
Tested-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Andreas Bießmann <andreas@biessmann.org>

common/bootm.c

@@ -445,7 +445,7 @@ static int bootm_load_os(bootm_headers_t *images, unsigned long *load_end,
 		bootstage_error(BOOTSTAGE_ID_DECOMP_IMAGE);
 		return err;
 	}
-	flush_cache(load, *load_end - load);
+	flush_cache(load, ALIGN(*load_end - load, ARCH_DMA_MINALIGN));
 
 	debug("   kernel loaded at 0x%08lx, end = 0x%08lx\n", load, *load_end);
 	bootstage_mark(BOOTSTAGE_ID_KERNEL_LOADED);