alpine-hal SerDes file was omitted in the previous commit.
Files added here.
All unnecessary (old) files were also removed.
Merge from vendor-sys, r306017
Files required for the NIC driver
Import from vendor-sys/alpine-hal/2.7
SVN rev.: 294828
HAL version: 2.7
Obtained from: Semihalf
Sponsored by: Annapurna Labs