bind: remove nslookup from FILES

The nslookup had been disabled from 2010 (or earlier), but it still in
FILES_${PN}-utils, we need remove it.

(From OE-Core rev: 3bf1f39d918a428246df774c8d306bcfe40ddbdd)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>