mfd: Remove omap-usb-host magic numbers for dev dma mask

Remove the hardcoded magic values for dma mask and use the dma
mask api/macro available.

Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>