remoteproc: ti_k3_arm64: Change the startup of arm64 core

Configuring master firewalls require the power of the cluster to be
enabled before configuring them, change the load of rproc to configure
the gtc clocks and start the cluster along with configuring the boot
vector.

The start of rproc will only start the core.

Signed-off-by: Manorit Chawdhry <m-chawdhry@ti.com>