bxe: Program the common RSS key in searcher byte order

[kbowling]

Summary

Use the common RSS key instead of generating private random words.
Reverse the bytes before passing the key to the shared code, which copies
the supplied bytes directly into the firmware request.  The searcher
consumes this array in reverse order; a raw copy of the common key would
not produce matching Toeplitz hashes.

The hardware ordering is documented by Linux commit
d682d2bdc30650a5c7ce9908ab83ab674b658744 ("bnx2x: byte swap rss_key to
comply to Toeplitz specs").  Keep the conversion in the FreeBSD caller
rather than changing the shared-code interface.

Preserve the config_hash gate, including the PMF-only key programming
on 57710/57711, and leave hash types and indirection policy unchanged.

MFC after:      2 weeks
Sponsored by:   BBOX.io