clk: renesas: r9a06g032: Add restart handler

clk: renesas: r9a06g032: Add restart handler

The SYSCTRL module also does reset handling. Start supporting that by
allowing software resets which can then be utilized by a restart
handler. Finally 'reboot' will do something useful on RZ/N1D. Watchdog
support to be added later.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20241128091113.24116-2-wsa+renesas@sang-engineering.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>