more clocks and the necessary binding header to easily access the cru-clocks
small comment to make the meaning of the RK2928 defines clearer
unfinished change to make the cpuclk callback usable for rk2928, rk3066 and rk3188
radxa: enable mmc slot
use the cru clocks and define sd0 pull settings according to the rk3188 trm default values