remoteproc: st: Fix indexing of memory-regions

The recent transition to use of_reserved_mem_region_to_resource()
changes the while loop to a for loop, but the increment of the "index"
variable was left behind at the end of the loop, as highlighted by the
following error/warning:

  error: variable 'index' is incremented both in the loop header and in the loop body [-Werror,-Wfor-loop-analysis]

Drop the extra increment to avoid skipping over every other
memory-region in the loop.

Fixes: 67a7bc7f03 ("remoteproc: Use of_reserved_mem_region_* functions for "memory-region"")
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20251126-st-remoteproc-double-index-v1-1-3b0a8b21ac18@oss.qualcomm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/remoteproc/st_remoteproc.c

@@ -155,7 +155,6 @@ static int st_rproc_parse_fw(struct rproc *rproc, const struct firmware *fw)
 			return -ENOMEM;
 
 		rproc_add_carveout(rproc, mem);
-		index++;
 	}
 
 	return rproc_elf_load_rsc_table(rproc, fw);