The CCS spec supports a lot of variation in the PLL. Split the PLL in
front and back parts to better prepare for supporting it.

Also use CCS compliant naming for IP and OP PLL frequencies (i.e. include
"clk" in the name).
Signed-off-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>