staging: csr: remove CsrStrNcpy

A few other functions were using it, but no one was calling them, so
remove them as well:
	CsrUtf8StrNCpy()
	CsrUtf8StrNCpyZero()
	CsrUtf8StringConcatenateTexts()

Cc: Mikko Virkkilä <mikko.virkkila@bluegiga.com>
Cc: Lauri Hintsala <Lauri.Hintsala@bluegiga.com>
Cc: Riku Mettälä <riku.mettala@bluegiga.com>
Cc: Veli-Pekka Peltola <veli-pekka.peltola@bluegiga.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>