Comment 13 for bug 1838725

Thanks Daniel, the corresponding upstream commit is
https://gitlab.freedesktop.org/plymouth/plymouth/-/commit/75204a251

The description indeed matches what is described on this bug

'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.'