cxgbe(4): Updated register dumps.

• Get the list of registers to read during a regdump from the shared code instead of the OS specific code. This follows a similar move internally. The shared code includes the list for T6.

• Update cxgbetool to be able to decode T5 VF, T6, and T6 VF register dumps (and catch up with some updates to T4 and T5 register decode).

Obtained from: Chelsio Communications
Sponsored by: Chelsio Communications