Qemu has an automatic dependency on valgrind which cannot be disabled, which
causes non-deterministic builds and build failures. As Valgrind wasn't enabled
previously make this deterministic by forcibly disabling it.
(From OE-Core rev: 33960902b9c36575ddda3d926d70fa13bbad85f6)
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>