imx8mq_pins: fix configuration for UART4 on ECSPI2 pads
When routing UART4 using the ECSPI2 pads, register IOMUXC_UART4_RXD_SELECT_INPUT (offset 0x050C) should be changed only when dealing with RX, as its name suggests.
When routing UART4 using the ECSPI2 pads, register IOMUXC_UART4_RXD_SELECT_INPUT (offset 0x050C) should be changed only when dealing with RX, as its name suggests.