arm64: dts: ti: k3-j721s2-common-proc-board: Add main_i2c4 instance

arm64: dts: ti: k3-j721s2-common-proc-board: Add main_i2c4 instance

Add dt node for main_i2c4 instance along with required pinmuxing.
Also add the gpio expander 'exp4' required by display connector.

Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Tested-by: Harikrishna Shenoy <h-shenoy@ti.com>
Reviewed-by: Harikrishna Shenoy <h-shenoy@ti.com>
Reviewed-by: Udit Kumar <u-kumar1@ti.com>
Link: https://lore.kernel.org/r/20250716060114.52122-5-j-choudhary@ti.com
Signed-off-by: Nishanth Menon <nm@ti.com>