plymouthd.defaults: Bump default DeviceTimeout to 8 seconds

The amdgpu driver needs up to 5 seconds to initialize / boot some
AMD GPUs, which makes our 5 second timeout much too close to the actual
needed time, leading to systems where sometimes the boot is fine and the
next boot we fallback to a text based splash because we won the race from
the GPU probe code.

This commit bumps the default DeviceTimeout to 8 seconds giving us a
decent marging here without making it overly long.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1737221
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

src/plymouthd.defaults

@@ -3,4 +3,4 @@
 [Daemon]
 Theme=spinner
 ShowDelay=0
-DeviceTimeout=5
+DeviceTimeout=8