dependency.  Non-legacy systems may have system memory
at 0xA0000, and if that's the case, we don't want to install the
VGA console.

Restructured conswitchp init slightly so that if both
CONFIG_DUMMY_CONSOLE and CONFIG_VGA_CONSOLE
are defined, conswitchp is always set to something, even if we
don't find VGA at 0xA0000.

This work is due to Alex Williamson (alex_williamson@hp.com).