commit a011e213 upstream.

This avoids following kernel crash when try to playback on arm64

[  107.497203] [<ffffffc00046b310>] snd_pcm_mmap_data_fault+0x90/0xd4
[  107.503405] [<ffffffc0001541ac>] __do_fault+0xb0/0x498
[  107.508565] [<ffffffc0001576a0>] handle_mm_fault+0x224/0x7b0
[  107.514246] [<ffffffc000092640>] do_page_fault+0x11c/0x310
[  107.519738] [<ffffffc000081100>] do_mem_abort+0x38/0x98

Tested: backported to 3.14 and tried to playback on arm64 machine
Signed-off-by: Anatol Pomozov <anatol.pomozov@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>