riscv: dts: spacemit: add UART resets for Soc K1

riscv: dts: spacemit: add UART resets for Soc K1

The UARTs in the SpacemiT K1 device tree are probed by the 8250_of driver,
but without reset lines they remain non-functional.

Add reset control entries so that the UARTs can operate when mapped to
devices. UART0 is already de-asserted by the bootloader, but include its
reset as well to avoid relying on bootloader state.

Tested on Orange Pi RV2 and Banana Pi BPI-F3 boards, with UART9 enabled
and verified functional.

Signed-off-by: Hendrik Hamerlinck <hendrik.hamerlinck@hammernet.be>
Reviewed-by: Yixun Lan <dlan@gentoo.org>
Link: https://lore.kernel.org/r/20250821152619.597051-1-hendrik.hamerlinck@hammernet.be
Signed-off-by: Yixun Lan <dlan@gentoo.org>