ply-device-manager: Also ignore SimpleDRM devs in coldplug enumeration path

ply-device-manager: Also ignore SimpleDRM devs in coldplug enumeration path

Plymouth has 2 hw discovery paths:
1. Enumerating devices already known by udev at plymouth startup
2. Devices which are hotplugged after startup

At boot we have udevd which is enumerating hw and plymouthd racing
with each other, which means that plymouthd may discover the new
SimpleDRM device through either 1. or 2.

Before this patch a check for SimpleDRM was missing from path 1, causing
it to be treated as a normal device instead of being ignored as intended:

plymouth-debug.log for the simpledrm being enumerated in path 1:

ply-device-manager.c:344: create_devices_for_subsystem:
 found device /sys/devices/platform/simple-framebuffer.0/drm/card0
ply-device-manager.c:351: create_devices_for_subsystem:
 device is initialized
ply-device-manager.c:360: create_devices_for_subsystem:
 found node /dev/dri/card0
ply-device-manager.c:283: create_devices_for_udev_device:
 found DRM device /dev/dri/card0
ply-device-manager.c:885: create_devices_for_terminal_and_rende:
 creating devices for /dev/dri/card0 (renderer type: 1)

plymouth-debug.log for the simpledrm *not* being enumerated in path 1:

ply-device-manager.c:344: create_devices_for_subsystem:
 found device /sys/devices/platform/simple-framebuffer.0/drm/card0
ply-device-manager.c:367: create_devices_for_subsystem:
 it's not initialized

followed by path 2 enumerating the device very shortly after this:

ply-device-manager.c:532: on_udev_event:
 got add event for device /dev/dri/card0
ply-device-manager.c:462: verify_add_or_change:
 ignoring since we only handle SimpleDRM devices after timeout

Note how path 2 does correctly ignore SimpleDRM devices, where as
path 1 does not. This commit fixes this by moving the verify_drm_device()
check in to create_devices_for_udev_device() which runs in both paths.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=2127663
Reported-by: Michael Catanzaro <mcatanza@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>