reset: thead: Add TH1520 reset controller driver

reset: thead: Add TH1520 reset controller driver

Add reset controller driver for the T-HEAD TH1520 SoC that manages
hardware reset lines for various subsystems. The driver currently
implements support for GPU reset control, with infrastructure in place
to extend support for NPU and Watchdog Timer resets in future updates.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
Link: https://lore.kernel.org/r/20250303152511.494405-3-m.wilczynski@samsung.com
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>