mfd: omap-usb-tll: HOST TLL platform driver

The platform driver for the TLL component of the OMAP USB host controller
is implemented. Depending on the TLL hardware revision , the TLL channels
are configured. The USB HS core driver uses this driver through exported
APIs from the TLL platform driver.
usb_tll_enable and usb_tll_disble are the exported APIs of the USB TLL
platform driver.

Signed-off-by: Keshava Munegowda <keshava_mgowda@ti.com>
Reviewed-by: Partha Basak <parthab@india.ti.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>