[nrf fromlist] drivers: serial: nrfx: Use legacy shim by default

So far new platforms did not use legacy shim but it shall
be now a default uart shim for all platforms.

Upstream PR: zephyrproject-rtos/zephyr#75462

Signed-off-by: Krzysztof Chruściński <[email protected]>

Author: nordic-krch

drivers/serial/Kconfig.nrfx

@@ -31,8 +31,6 @@ config UART_NRFX_UARTE
 config UART_NRFX_UARTE_LEGACY_SHIM
 	bool "Legacy UARTE shim"
 	depends on UART_NRFX_UARTE
-	depends on !SOC_SERIES_NRF54HX || RISCV
-	depends on !SOC_SERIES_NRF92X || RISCV
 	default y
 
 config UART_NRFX_UARTE_ENHANCED_RX