configs: j721e_evm: Add Main R5FSS1 Core1 to default rproc boot list

The default rproc list currently used by A72 U-Boot to boot various
remote processors include the Main R5FSS0 (Split-mode) Core1, Main
R5FSS1 (LockStep mode) Core0 and the three DSPs. The Main R5FSS1 cluster
is configured for Split mode by default in the dts now, so add the
Main R5FSS1 Core1 (rproc #5) to the default rproc boot list. This
core is now booted after the Main R5FSS1 Core0 and before the DSPs.

The order of the rprocs to boot can always be changed at runtime if
desired by overwriting the 'rproc_fw_binaries' environment variable
at U-boot prompt. Note that the R5FSS Core1 cannot be booted before
its associated Core0.

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