mfd: omap-usb-tll: Convert to devm_ioremap_resource()

Use the newly introduced devm_ioremap_resource() instead of
devm_request_and_ioremap() which provides more consistent error handling.

devm_ioremap_resource() provides its own error messages; so all explicit
error messages can be removed from the failure code paths.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Acked-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>