Support the setting of additional AHCI controller parameters.

Allow the serial number, firmware revision, model number and nominal media
rotation rate (nmrr) parameters to be set from the command line.

Note that setting the nmrr value can be used to indicate the AHCI
device is an SSD.

Submitted by: Wanpeng Qian
Reviewed by: jhb, grehan (bhyve)
Approved by: jhb, grehan
MFC after: 3 weeks
Relnotes: yes
Differential Revision: https://reviews.freebsd.org/D24174