Modules: ES18xx driver

Forth of 4 es18xx.c patches culminating in Zoom Video support.

This patch adds Zoom Video support for those chipsets that support it.

Testing:
This work was initially done on the source from the Debian Sarge ALSA
package, then tested
on an ES1879. I could not test the Zoom Video function for an ES1878 or
ES1869.
Patches were created against the Sarge code and then edited to apply
correctly to the
ALSA cvs code. Lastly the patched ALSA cvs code was test for successful
compilation.
No additional testing was done on the ALSA cvs version.

One quirk (noted in my comments below) is that apparently the datasheet
is wrong
for one of the ES1879 Zoom Video 'enable' bits, because
 1) if you set this bit it messes up PCM playback (speaker_test play a
lower frequency)
 2) even if you don't set this bit Zoom Video still works.
I added a control to toggle the bit on just in case there might be a
version of the
ES1879 that requires it, but I expect noone will need it.
Signed-off-by: Mark Salazar <markTheCoder@justmyself.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>