atl1c: remove SMB/CMB DMA related code

l1c & later chips don't support DMA for SMB.
CMB is removed from hardware.
reg(15C8) is used to trig interrupt by tpd threshold.

Signed-off-by: xiong <xiong@qca.qualcomm.com>
Tested-by: Liu David <dwliu@qca.qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>