Since mmap for userspace is based on page alignment, add page alignment
for iram alloc from pool, otherwise, some good data located in the same
page of dmab->area maybe touched wrongly by userspace like pulseaudio.

Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1608221747-3474-1-git-send-email-yibin.gong@nxp.com


Signed-off-by: Takashi Iwai <tiwai@suse.de>