MFC r344198:
GC ATA_REQUEST_TIMEOUT option remnants

It was removed from code in r249083 and from sys/conf/options in r249213.

PR: 193935, 222170

MFC r286814, r286816: Remove UMA allocation of ATA requests.

After CAM replaced old ATA stack, this driver processes no more then one
request at a time per channel. Using UMA after that is overkill, so
replace it with simple preallocation of one request per channel.

MFC r280451:
Remove from legacy ata(4) driver support for hardware, supported by newer
and more functional drivers ahci(4), siis(4) and mvs(4).

This removes about 3400 lines of code, unused since FreeBSD 9.0 release.

MFC r279963: Fix SATA Gen3 speed constants.

MFC r286814, r286816: Remove UMA allocation of ATA requests.

After CAM replaced old ATA stack, this driver processes no more then one
request at a time per channel. Using UMA after that is overkill, so
replace it with simple preallocation of one request per channel.

MFC r280451:
Remove from legacy ata(4) driver support for hardware, supported by newer
and more functional drivers ahci(4), siis(4) and mvs(4).

This removes about 3400 lines of code, unused since FreeBSD 9.0 release.

MFC r279963: Fix SATA Gen3 speed constants.