runqemu: use "raw" instead of "bin" for ovmf

bin is not an acceptable format for qemu and will throw an error is set.
The correct format in this case is raw.

(From OE-Core rev: cd279aeb986b4676ea8ecb1e7b12c7e29e83460a)

Signed-off-by: Jon Mason <jon.mason@arm.com>
Change-Id: I9d78e356d39ecb15bef886c19870b029d9badd65
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu

@@ -1345,6 +1345,8 @@ class BaseConfig(object):
 
         for ovmf in self.ovmf_bios:
             format = ovmf.rsplit('.', 1)[-1]
+            if format == "bin":
+                format = "raw"
             self.qemu_opt += ' -drive if=pflash,format=%s,file=%s' % (format, ovmf)
 
         self.qemu_opt += ' ' + self.qemu_opt_script