remoteproc: k3-r5: Fix rproc init failure on Split-mode _only_ devices

The R5F subsystem/cluster on K3 SoCs can support both LockStep and
Split-modes (superset) or just Split-mode depending on an eFUSE
capability register. The LockStep configuration bit is Read-only
though on Split-mode _only_ devices and as such the System Firmware
does not allow the LockStep mode bit to be configured on such devices.
The current logic in k3_r5f_rproc_configure() fails on Split-mode
devices because of this unconditional programming of the LockStep
mode bit, and results in the probe failure shown during the
"rproc init" step at U-Boot prompt.

Fix this by limiting the LockStep mode bit clear configuration only on
devices supporting both LockStep/Split-modes.

Fixes: 4c850356 ("remoteproc: Introduce K3 remoteproc driver for R5F subsystem")
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>