uint64_t->target_addr_t for stack pointers.

This might be incomplete. It's just a quick attempt to reduce some of
the difference between riscv-openocd and mainline. Other stack pointers
can be updated as I come across them.

Change-Id: Id3311b8a1bb0667f309a26d36b67093bfeb8380a
Signed-off-by: Tim Newsome <tim@sifive.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6586
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/rtos/rtos.c

@@ -616,7 +616,7 @@ int rtos_generic_stack_read(struct target *target,
 		LOG_OUTPUT("\r\n");
 #endif
 
-	int64_t new_stack_ptr;
+	target_addr_t new_stack_ptr;
 	if (stacking->calculate_process_stack) {
 		new_stack_ptr = stacking->calculate_process_stack(target,
 				stack_data, stacking, stack_ptr);