support/testing: test_ubi: add image format on the qemu command line

Adding the Image format on the Qemu command line avoid this warning:

"WARNING: Image format was not specified for 'output/TestUbi/images/rootfs.ubi' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions."

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
(cherry picked from commit 1ab2dd6aa5)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/testing/tests/fs/test_ubi.py

@@ -32,7 +32,7 @@ class TestUbi(infra.basetest.BRTest):
                            kernel_cmdline=["root=ubi0:rootfs",
                                            "ubi.mtd=0",
                                            "rootfstype=ubifs"],
-                           options=["-drive", "file={},if=pflash".format(img)])
+                           options=["-drive", "file={},if=pflash,format=raw".format(img)])
         self.emulator.login()
         cmd = "mount | grep 'ubi0:rootfs on / type ubifs'"
         _, exit_code = self.emulator.run(cmd)