arm64: dts: ti: k3-j721e-sk: Add pinmux for RPi Header

Add pinmux required to bring out i2c5 and gpios on 40 pin RPi header on sk
board

Signed-off-by: Sinthu Raja <sinthu.raja@ti.com>
Signed-off-by: Rahul T R <r-ravikumar@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20221107070009.11500-3-r-ravikumar@ti.com