regulator: twl: add clk32kg to twl-regulator

In OMAP4 Blaze and Panda, 32KHz clock to WLAN is supplied from Phoenix
TWL6030. The 32KHz clock state (ON/OFF) is configured in
CLK32KG_CFG_[GRP, TRANS, STATE] register. This follows the same register
programming model as other regulators in TWL6030. So add CLK32KG as pseudo
regulator.

Signed-off-by: Balaji T K <balajitk@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>