mmc: mmc_test: align max_seg_size

If max_seg_size is unaligned, mmc_test_map_sg() may create sg element
sizes that are not aligned with 512 byte. Fix, align max_seg_size at
mmc_test_area_init().
Signed-off-by: Per Forlin <per.forlin@stericsson.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/card/mmc_test.c

@@ -1581,6 +1581,7 @@ static int mmc_test_area_init(struct mmc_test_card *test, int erase, int fill)
 
 	t->max_segs = test->card->host->max_segs;
 	t->max_seg_sz = test->card->host->max_seg_size;
+	t->max_seg_sz -= t->max_seg_sz % 512;
 
 	t->max_tfr = t->max_sz;
 	if (t->max_tfr >> 9 > test->card->host->max_blk_count)