The PPC405 hard core is used in both the Virtex-II Pro and Virtex 4 FX
FPGAs.  This patch cleans up the Virtex naming convention to reflect more
than just the Virtex-II Pro.

Rename files virtex-ii_pro.[ch] to virtex.[ch]
Rename config value VIRTEX_II_PRO to XILINX_VIRTEX
Signed-off-by: Grant C. Likely <grant.likely@secretlab.ca>
Signed-off-by: Paul Mackerras <paulus@samba.org>