matroxfb: fix incorrect use of memcpy_toio()

Screen is completely corrupted since 2.6.34.  Bisection revealed that it's
caused by commit 6175ddf0 ("x86: Clean up mem*io functions.").

H.  Peter Anvin explained that memcpy_toio() does not copy data in 32bit
chunks anymore on x86.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: <stable@kernel.org>		[2.6.34.x, 2.6.35.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>