soc: riscv: litex: Add helpers for accessing CSRs
soc: riscv: litex: Add helpers for accessing CSRs

Depending on LiteX configuration, CSRs
(control&status registers) might be split
into several consecutive registers.

This introduces common helper functions
for all LiteX drivers providing access
to CSRs for a default LiteX configuration
(data_width = 8bit, bus_width = 32bit).

Signed-off-by: Mateusz Holenko <1a79f421828d0048009fccfd7504972981cac7dd@antmicro.com>

nashif/zephyr,Vudentz/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,Vudentz/zephyr