bfin_mac: use the newer CLKBUFOE bit name via asm/dpmc.h

This driver tweaks VR_CTL, so pull in the header for the bit defines.
Also switch to the new define name as the old one has gone away.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: David S. Miller <davem@davemloft.net>