ALSA: pcm: Use ERESTARTSYS instead of EINTR in OSS emulation

commit c64ed5dd9feba193c76eb460b451225ac2a0d87b upstream.

Fix the last standing EINTR in the whole subsystem.  Use more correct
ERESTARTSYS for pending signals.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>