Blackfin: add MDMA defines to make cross-variant coding easier

Add some defines to make the BF538/BF561 look like most other Blackfin
parts in that it has a MDMA0 channel available for low level init.

Signed-off-by: Graf Yang <graf.yang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
5 files changed