src/server: Fix memory leak of reg_list

memory leak of reg_list when local_list realloc fail.

Signed-off-by: panciyan <panciyan@eswincomputing.com>
Change-Id: I6b09137ecd132ab326205f5a575a38bcc82e8469
Reviewed-on: https://review.openocd.org/c/openocd/+/7566
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/server/gdb_server.c

@@ -2348,6 +2348,7 @@ static int smp_reg_list_noread(struct target *target,
 						local_list = realloc(local_list, combined_allocated * sizeof(struct reg *));
 						if (!local_list) {
 							LOG_ERROR("realloc(%zu) failed", combined_allocated * sizeof(struct reg *));
+							free(reg_list);
 							return ERROR_FAIL;
 						}
 					}