The MCU RGMII MCU_RGMII1_TXC pin is defined as input by mistake, although
this does not make any difference functionality wise it's better to update
to avoid confusion.

Hence fix MCU RGMII MCU_RGMII1_TXC pin pinmux definitions to be an output
in K3 am654x/j721e/j7200 board files.
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20210526132041.6104-1-grygorii.strashko@ti.com