ALSA: ctxfi: Fallback DMA mask to 32bit

ALSA: ctxfi: Fallback DMA mask to 32bit

BugLink: http://bugs.launchpad.net/bugs/1672544
commit 15c75b09f8d190f89ab4db463b87d411ca349dfe upstream.

Currently ctxfi driver tries to set only the 64bit DMA mask on 64bit
architectures, and bails out if it fails.  This causes a problem on
some platforms since the 64bit DMA isn't always guaranteed.  We should
fall back to the default 32bit DMA when 64bit DMA fails.

Fixes: 6d74b86d3c0f ("ALSA: ctxfi - Allow 64bit DMA")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>