clocksource/drivers/ralink: Fix resource leaks in init error path

clocksource/drivers/ralink: Fix resource leaks in init error path

The ralink_systick_init() function does not release all acquired resources
on its error paths. If irq_of_parse_and_map() or a subsequent call fails,
the previously created I/O memory mapping and IRQ mapping are leaked.

Add goto-based error handling labels to ensure that all allocated
resources are correctly freed.

Fixes: 1f2acc5a8a0a ("MIPS: ralink: Add support for systick timer found on newer ralink SoC")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://patch.msgid.link/20251030090710.1603-1-vulab@iscas.ac.cn