arm64: dts: ti: k3-j721e-main: Update the compatible for ICSS IEP nodes

Update the compatible for all ICSSG IEP nodes to ti,am654-icss-iep, so
that icss_iep driver can be probed.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>