alpha: sort scr_mem{cpy,move}w() out

alpha: sort scr_mem{cpy,move}w() out

Take scr_memmove() out of line, make both it and scr_memcpyw()
conditional upon VGA_CONSOLE or MDA_CONSOLE (if neither is
selected, we are certain to be working with the kernel-allocated
buffer rather than VRAM and defaults will work just fine).

That allows to clean vt_buffer.h, but that's a separate story

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>