Mostly fixes to allow driver to work with GMA4500, at least with 16-bit modes

Mostly fixes to allow driver to work with GMA4500, at least with 16-bit modes
on built-in panels:
 - Adjusted for different PCI BAR layout of later chips.
 - Later chips require virtual address of cursor image instead of physical
   address.
 - Fixed delay_#?() and G45_parse_ddc() return types.
 - Flush command ring at end of CopyBox method (fixes menu display glitches
   on GMA4500).
 - Write NULL surface address on pipe B to trigger update of other display
   registers.
 - Don't call super method twice in bitmap class's Set method.
 - Flush command ring at end of DrawPixel method (fixes window-drag outline
   on GMA4500).
 - Fixed typo: '=!' -> '!='.
 - Flush command ring at end of FillRect and DrawLine methods (fixes shell
   cursor on GMA4500).
 - Fixed some warnings.

git-svn-id: https://svn.aros.org/svn/aros/trunk/AROS@37293 fb15a70f-31f2-0310-bbcc-cdcc74a49acc