Centralize determination of boot firmware (UEFI vs. BIOS/CSM) into a
function x86_bootmethod() and fix deviations from style(9).


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273003 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Use the FIFOs in the imx5/imx6 uart hardware instead of interrupting on
each byte sent or received.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273004 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Only allow ZFS boot on GPT; the MBR ZFS bootblocks cannot be installed using
gpart bootcode as /boot/zfsboot needs to be split into multiple pieces by
hand and copied to different areas of the partition.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273005 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f