scripts/runqemu: Fix logic error causing failures with MACHINE from the environment

MACHINE=qemux86-64 oe-selftest -r runqemu.RunqemuTests.test_boot_machine_slirp_qcow2

fails yet

oe-selftest -r runqemu.RunqemuTests.test_boot_machine_slirp_qcow2

with MACHINE in local.conf would work.

It turns out that:

runqemu slirp wic.qcow2 qemux86-64

works but:

MACHINE=qemux86-64 runqemu slirp wic.qcow2 qemux86-64

does not.

The reason are the misplaced return statements in runqemu, its skipping a block
of logic when MACHINE is set in the environment when it shouldn't. Fix this.

(From OE-Core rev: 98d113ae52cbbc88773a81a17b0933412a8e463b)

(From OE-Core rev: bf2ae1ca01edf02a930d70e50b8e1e71f7ec2237)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu

@@ -474,14 +474,11 @@ class BaseConfig(object):
                                        "Try 'runqemu help' on how to use it" % \
                                         (unknown_arg, arg))
         # Check to make sure it is a valid machine
-        if unknown_arg:
-            if self.get('MACHINE') == unknown_arg:
-                return
+        if unknown_arg and self.get('MACHINE') != unknown_arg:
             if self.get('DEPLOY_DIR_IMAGE'):
                 machine = os.path.basename(self.get('DEPLOY_DIR_IMAGE'))
                 if unknown_arg == machine:
                     self.set("MACHINE", machine)
-                    return
 
             self.check_arg_machine(unknown_arg)