Increased the number of ATM channels that the Freescale Driver can support

- Reduced the number of Rx buffers allocated per channel
- Can support almost 256 ATM channels before memory exhaustion
Prevent divide by zero when calculating PCR rates
Set the ATM MAC address from the flattened device tree
FUA Driver - split RX & TX buffer descriptor allocation sizes

- Increase TX BD count to allow for multiple high rate transmits
- Reduce RX BD and buffer allocation to prevent memory exhaustion
Tune UBR PCR rates to allow for max throughput
Fixed FUA Oops bug when running aburst UBR traffic directly

- FUA interrupt handling code for errors was accessing null pointers
Fixed CBR rate degradation vs number of UBR channels

- Reduced APC priority table levels from 3 to 2
- Enable AVCF automatic disabling of VCON for UBR channels
- Re-start UBR transmit if channel was disabled via AVCF