mx51/iomux: Fix mux mode and input path for two pads

For pad EIM_D27 to work in UART3_RTS mode, the input path should be
3 instead of 0; for pad USBH1_STP to work in GPIO_1_27 mode, the mux
value should be 2 instead of 8.

Signed-off-by: Jason Wang <jason77.wang@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>