atl1c: split 2 32bit registers of TPD to 4 16bit registers

TPD producer/consumer index is 16bit wide.
16bit read/write reduce the dependency of the 2 tpd rings (hi and lo)
rename reg(157C/1580) to keep name coninsistency.

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>