usb: host: ehci-exynos: Use devm_ioremap_resource instead of devm_ioremap

Using devm_ioremap_resource() API should actually be preferred over
devm_ioremap(), since the former request the mem region first and then
gives back the ioremap'ed memory pointer.
devm_ioremap_resource() calls request_mem_region(), therby preventing
other drivers to make any overlapping call to the same region.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>