Staging: vme: change to VME_BUS

Turns out the m68k arch already has a CONFIG_VME, so use
CONFIG_VME_BUS instead.

Thanks to Geet Uytterhoeven for pointing this out.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>