MIPS: JZ4770: Declare jz_pm_init() in its own header

It was declared in the CPM header, but it doesn't belong there.
MIPS: JZ4770: Split LCD controller I/O space into 3 regions

The TV encoder registers are after the normal LCDC registers but before
the "*0_PART2" registers used in foreground 0 divide mode.

The framebuffer driver currently doesn't use any registers after the
first region, so no changes were required there.
fb: JZ4770: Switch to using foreground 1 layer in OSD mode

Previously, non-OSD mode was used. However, in the future we want to
be able to show OSD messages from pwswd or perhaps a virtual keyboard.
Also the OSD is a good way to show a splash screen without the logo
trickery we previously used.

Additionally, the IPU can output to foreground layer 1, which would
enable us to use hardware scaling.

Finally, TV-out seems to work only in OSD mode: in non-OSD mode the
colors are wrong no matter how I configure the LCDC. Possibly the TV
encoder only accepts YUV input and our frame buffer is in RGB; there
is a flag to convert RGB to YUV but that flag only works in OSD mode.