sparc32: ledma extra registers

sparc32: ledma extra registers

ledma has 0x20 bytes of registers according to OBP, and at least Solaris9
reads the 5th register which is beyond what we've mapped.  So let's setup
a flag (inspired by a previous patch from Blue Swirl) to identify ledma
from espdma, and map another 16 bytes of registers which return 0.

Signed-off-by: Bob Breuer <[email protected]>
Signed-off-by: Blue Swirl <[email protected]>