Introduce INP6_PCBHASHKEY macro. Replace usage of hardcoded part of
IPv6 address as hash key in all places.

Obtained from:	Yandex LLC


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271386 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Remove unused arguments for VOP_GETPAGES(), VOP_PUTPAGES().


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271387 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f