powerpc/512x: clk: support MPC5121/5123/5125 SoC variants

powerpc/512x: clk: support MPC5121/5123/5125 SoC variants

improve the common clock support code for MPC512x

- expand the CCM register set declaration with MPC5125 related registers
  (which reside in the previously "reserved" area)
- tell the MPC5121, MPC5123, and MPC5125 SoC variants apart, and derive
  the availability of components and their clocks from the detected SoC
  (MBX, AXE, VIU, SPDIF, PATA, SATA, PCI, second FEC, second SDHC,
  number of PSC components, type of NAND flash controller,
  interpretation of the CPMF bitfield, PSC/CAN mux0 stage input clocks,
  output clocks on SoC pins)
- add backwards compatibility (allow operation against a device tree
  which lacks clock related specs) for MPC5125 FECs, too

telling SoC variants apart and adjusting the clock tree's generation
occurs at runtime, a common generic binary supports all of the chips

the MPC5125 approach to the NFC clock (one register with two counters
for the high and low periods of the clock) is not implemented, as there
are no users and there is no common implementation which supports this
kind of clock -- the new implementation would be unused and could not
get verified, so it shall wait until there is demand

Signed-off-by: Gerhard Sittig <gsi@denx.de>
Acked-by: Mike Turquette <mturquette@linaro.org>
Signed-off-by: Anatolij Gustschin <agust@denx.de>