armv7R: K3: Add support for jumping to firmware

MCU Domain rf50 is currently shutting down after loading the ATF.
Load elf firmware and jump to firmware post loading ATF.

ROM doesn't enable ATCM memory, so make sure that firmware that
is being loaded doesn't use ATCM memory or override SPL.

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