Revert "lib: Sparc's strncpy_from_user is generic enough, move under"

This reverts commit 95eac6a53f04524a03f318242db4577cf1f3117f.

Conflicts:
	lib/Kconfig
	lib/Makefile
	lib/strncpy_from_user.c
Revert "word-at-a-time: make the interfaces truly generic"

This reverts commit be9a9be621268263920b5389139fd060793dc65c.