qemu 0.14 does not need --cross-prefix switch as it uses CC environment
variables (and friends) which contains the cross prefix already.
(From OE-Core rev: c9ead26abae18397fcf0e07ff278bb9052d5b8f3)
Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>