omap4: Adding PBIAS Configuration for MMC1 Controller

In OMAP4, MMC1 PBIAS and its associated IO is software-controlled
by CONTROL_PBIAS and CONTROL_MMC1 registers. This patch adds PBIAS
configuration for MMC1 Controller during power-ON and power-OFF
of regulator.

Signed-off-by: Kishore Kadiyala <kishore.kadiyala@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>