ASoC: twl6040: Add VDDHF regulator

Use regulator framework to enable/disable VDDHF voltage supply
for handsfree drivers. Not providing a valid regulator for VDDHF
through regulator framework doesn't have any negative impact as
long as VDDHF is actually supplied by some other way (e.g. voltage
supply enabled through bootloader or machine initialization).

Ported from p-android-omap-2.6.35

Change-Id: I9df90a695ed9afcb6da916fb53bb3965c5292226
Signed-off-by: Girish S G <girishsg@ti.com>
Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>
Signed-off-by: Akash Choudhari <akashc@ti.com>
Signed-off-by: Girish S Ghongdemath <girishsg@ti.com>
Signed-off-by: Gabriel M. Beddingfield <gabrbedd@ti.com>

Conflicts:
	sound/soc/codecs/twl6040.c
ASoC: twl6040: VDDHF as SUPPLY widget

VDDHF external boost supply was being enabled after and disabled before
handsfree driver as a strategy for pop noise reduction. This strategy
makes handsfree driver very susceptible to overcurrent events, so the
boost supply is converted to a SUPPLY widget to enable it before and
disable it after handsfree path.

Change-Id: I608b4b0f5cb3301053869ccd2732434efe276b81
Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>