drivers: remoteproc: xlnx: Fix uninitialized variable use

Fix following warning for clang compiler with W=1 option:
initialize the variable 'ret' to silence this warning
     907 |         int ret, i;
         |                ^
         |                 = 0

Fixes: a6b974b4 ("drivers: remoteproc: xlnx: Add Versal and Versal-NET support")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404231839.oHiY9Lw8-lkp@intel.com/Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
Link: https://lore.kernel.org/r/20240423170210.1035957-1-tanmay.shah@amd.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/remoteproc/xlnx_r5_remoteproc.c

@@ -904,7 +904,7 @@ static int zynqmp_r5_core_init(struct zynqmp_r5_cluster *cluster,
 {
 	struct device *dev = cluster->dev;
 	struct zynqmp_r5_core *r5_core;
-	int ret, i;
+	int ret = -EINVAL, i;
 
 	r5_core = cluster->r5_cores[0];