freedreno: Add A2xx REG_A2XX_RBBM_PM_OVERRIDE2 bitfields
Dmitry pointed me to
this has even more nice reg descriptions, might be worth looking into some day
required for https://lore.kernel.org/linux-arm-msm/20230223-topic-opp-v2-0-24ed24cd7358@linaro.org/ to rid magic values from a2xx_busy()