Add initial support for dynamic frequency switching on pieces of the imx
interconnect fabric.

All this driver does is set a clk rate based on an opp table, it does
not map register areas.
Signed-off-by: NLeonard Crestez <leonard.crestez@nxp.com>
Tested-by: NMartin Kepplinger <martin.kepplinger@puri.sm>
Acked-by: NChanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: NChanwoo Choi <cw00.choi@samsung.com>