MFC r272036:
Avoid calling vm_map_pmap_enter() for the MADV_WILLNEED on the wired
entry, the pages must be already mapped.

Approved by:	re (gjb)
MFC r272040:
When reporting some major UNIT ATTENTION condition, like POWER ON OCCURRED
or I_T NEXUS LOSS, clear all minor UAs for the LUN, redundant in this case.

All SAM specifications tell that target MAY do it, but libiscsi initiator
seems require it to be done, terminating connection with error if some more
UAs happen to be reported during iSCSI connection.

Approved by:	re (gjb)
MFC r272059:
Remake Linux' SOUND_MIXER_INFO IOCTL as a wrapper around new FreeBSD's one.

Submitted by:	Dmitry Luhtionov <dmitryluhtionov@gmail.com>

Approved by:	re (kib)