Currently, qemuppc prints warnings about gdk-pixbuf postinstalls
not working due to illegal instructions. This is due to qemu
running with the wrong cpu type. Add an option for ppc7400 so
that qemuppc works correctly.
(From OE-Core rev: 5995fdbe81799f1ecf5de722cb2eb95ccb2aa860)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>