ARM: imx: add clk-pllv1 type support

Instead of calling cpu_is_xxx() in clk-pllv1 driver, let's add clk-pllv1
type support to handle the difference/quirk in particular SoC designs.
Doing so will help get clk-pllv1 driver ready for being moved out of
arch/arm/mach-imx folder.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>