ALSA: sh: Use standard helper for buffer accesses

ALSA: sh: Use standard helper for buffer accesses

The SH DAC audio driver uses the kmalloc'ed buffer as the main PCM
buffer, and the data is transferred via hrtimer callbacks manually
from there to the hardware.  Meanwhile, some of its code are written
as if the buffer is on iomem and use the special helpers for the iomem
(e.g. copy_from_iter_toio() or memset_io()).  Those are rather useless
and the standard helpers should be used.

Similarly, the PCM mmap callback is set to a special one with
snd_pcm_lib_mmap_iomem, but this is also nonsense, because SH
architecture doesn't support this function, hence it leads just to
NULL -- the fallback to the standard helper.

This patch replaces those special setups with the standard ones.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202411281337.I4M07b7i-lkp@intel.com/
Link: https://patch.msgid.link/20241128104939.13755-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>