IGbE: Clean up debug printing and proprly account for copied bytes.

IGbE: Clean up debug printing and proprly account for copied bytes.

Some DPRINTFs were printing uninitalized values because the DPRINTFs were
always being printed even when the features they were printing weren't
being used. This change moves the DPRINTFs into the appropriate if blocks
and initializes the state variables correctly.

There also is a case where the offset into the packet could be calculated
incorrectly during a DMA that is fixed.