tests/qtest: prom-env-test: Use double quotes to pass the prom-env option

Single quotes like -prom-env 'nvramrc=cafec0de 4000 l!' in the arguments
are not removed in the Windows environment before it is passed to the
QEMU executable. Such argument causes a failure in the QEMU prom-env
option parser codes.

Change to use double quotes which works fine on all platforms.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220824094029.1634519-46-bmeng.cn@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/prom-env-test.c

@@ -58,8 +58,8 @@ static void test_machine(const void *machine)
             " -machine " PSERIES_DEFAULT_CAPABILITIES;
     }
 
-    qts = qtest_initf("-M %s -accel tcg %s -prom-env 'use-nvramrc?=true' "
-                      "-prom-env 'nvramrc=%x %x l!' ", (const char *)machine,
+    qts = qtest_initf("-M %s -accel tcg %s -prom-env \"use-nvramrc?=true\" "
+                      "-prom-env \"nvramrc=%x %x l!\" ", (const char *)machine,
                       extra_args, MAGIC, ADDRESS);
     check_guest_memory(qts);
     qtest_quit(qts);