ALSA: x86: Replace indirect register ops with direct calls

Now about the indirect register ops: they are replaced with direct
calls, too.

The read / write / modify ops are simply replaced with the
corresponding functions.  The difference is that we calculate the
offset inside the function now.  So all the had_config_offset
references in the caller side are dropped.  This also simplifies the
DP-audio check in hdmi_audio_write() and hdmi_audio_rmw().

The hdmi_audio_get_register_base is dropped since it's no longer used
when the base address and config offset are referred in the read/write
functions.

Signed-off-by: Takashi Iwai <tiwai@suse.de>