uboot-phytec

arm: dts: k3-j721e-common-proc-board: Mark main_uart0 as shared device

Main uart0 is used as debug console by both R5SPL and A72 bootloader and
Linux. So mark it as shared device so that power-domain request is
successful by both cores.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>