OvmfPkg/build.sh: use newer '-drive if=pflash' syntax when running qemu
Specify the firmware to use via the newer '-drive if=pflash' syntax
which allows specifying the raw format parameter. This
avoids warnings with newer version of QEMU.
Signed-off-by: Rebecca Cran <rebecca@bsdio.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>