sfxge(4): update hardware headers for Medford2

The changes to efx_regs_ef10.h are auto-generated and include:

• Updated event RX_L4_CLASS which is now 2 bits (was 3). The encoding of TCP, UDP and UNKNOWN are unchanged so the narrower Medford2 field definition is compatible with all controllers.
• Fix definition of FATSOv2 option descriptors. These were added manually and differ from the auto-generated values in some fields (not yet used in common code). The field definitions have been corrected to agree with the Linux net driver headers and SF-108452-SW.

The remaining changes adapt the common code to use the updated
headers.

Submitted by: Andy Moreton <amoreton at solarflare.com>
Sponsored by: Solarflare Communications, Inc.
Differential Revision: https://reviews.freebsd.org/D18161