net: stmmac: Add additional registers for dwmac1000_dma ethtool

Version 3.70a of the Designware has additional DMA registers so
add those to the ethtool DMA Register dump.
Offset 9  - Receive Interrupt Watchdog Timer Register
Offset 10 - AXI Bus Mode Register
Offset 11 - AHB or AXI Status Register
Offset 22 - HW Feature Register

Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
Acked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>