clk: rk3399: Add enable/disable clks

clk: rk3399: Add enable/disable clks

Yes, most of the high speed peripheral clocks
in rk3399 enabled by default.

But it would be better to handle them via clk
enable/disable API for handling proper reset
conditions like 'usb reset' over command line.

So, enable USB, GMAC clock via enable/disable ops.

Signed-off-by: Jagan Teki <[email protected]>
Tested-by: Suniel Mahesh <[email protected]> # roc-rk3399-pc
Tested-by: Suniel Mahesh <[email protected]> #roc-rk3399-pc
Reviewed-by: Kever Yang <[email protected]>