A zero value for dpi will lead to a division by zero in qemu_edid_dpi_to_mm().
Tested by runnig qemu-edid -dX, X = 0, 100.

Resolves: qemu-project/qemu#1249

Suggested-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Sebastian Mitterle <smitterl@redhat.com>
Message-Id: <20221011151216.64897-1-smitterl@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>