imx: imx7d: clock control module support
* Add Clock control module (CCM) support
* iMX7D SoC introduces 3 main clock sysmtem abstraction for clock
root frequency generation denominated clock slices.
Core clock slice: hihg speed clock for ARM core
Bus clock slice: for bus clocks
IP clock slice: Peripheral clocks
* At system boot ROM enables PLL_ARM, PLL_DDR, PLL_SYS, PLL_ENET
In u-boot, we have to:
- Configure PFD3- PFD7 for freq we needed in u-boot
- Set clock root for peripherals (ip channel)
Signed-off-by: Adrian Alonso <aalonso@freescale.com>
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Signed-off-by: Ye.Li <B37916@freescale.com>