Add new entries for Mystique AGP with the PCI ID 0x051e.

I don't actually have such boards but according to google they do exist.
Curiosly X.Org doesn't recognize that PCI ID.  And what's even more
interesting is that Matrox's own Windows drivers don't recognize it either.
After going through about a dozen different versions I did find one older
driver that does list this particular ID.  It is also listed in the pci.ids
file.

I'm not sure if non-220 AGP chips exist.  I left the chip revision check
intact for AGP chips nonetheless.
Signed-off-by: Ville Syrjl <syrjala@sci.fi>
Signed-off-by: Petr Vandrovec <petr@vandrovec.name>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>