MLK-9710-8 tcrypt: change memory allocation for test_ahash_speed output buffer

MLK-9710-8 tcrypt: change memory allocation for test_ahash_speed output buffer

Change allocation of the tcrypt module's test_ahash_speed() output buffer to
use kmalloc().  This avoids a segmentation fault when the buffer is used in a
dma_map_*() call.

Signed-off-by: Victoria Milhoan <vicki.milhoan@freescale.com>
(cherry picked from commit 3c8c56d1bd82433af6a565d183bdb632fd01a13a)