usb: chipidea: usb2: delete the redundant setting default DMA mask code

Similar as commit 2b2fe36d ("usb: chipidea: imx: delete the
redundant setting default DMA mask code"), the ci_hdrc_usb2 platform
device is also created by device tree, the default DMA mask should be
already set by of_dma_configure when the device are created. So delete
the redundant code at driver.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>