[ALSA] Reverted last patch for SNDCTL_DSP_GETOPTR fix & possible overflow fix

ALSA<-OSS emulation
This reverts the last patch which wrongly mixes bytes and frames.
The real culprit might be the 32-bit overflow, so the return expression uses
64-bit values now in snd_pcm_oss_bytes().

Signed-off-by: Jaroslav Kysela <perex@suse.cz>