drivers: remoteproc: xilinx: Fix carveout names

If the unit address is appended to node name of memory-region,
then adding rproc carveouts fails as node name and unit-address
both are passed as carveout name (i.e. vdev0vring0@xxxxxxxx). However,
only node name is expected by remoteproc framework. This patch moves
memory-region node parsing from driver probe to prepare and
only passes node-name and not unit-address

Fixes: 6b291e80

 ("drivers: remoteproc: Add Xilinx r5 remoteproc driver")
Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230311012407.1292118-5-tanmay.shah@amd.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>