psplash: Set a higher priority for psplash-oniro

This fixes build warning:

[log_check] Warn: update-alternatives: psplash has multiple providers
with the same priority

It is a workaround as the actual behaviour is yet to be understood.
There seems to be a bug or an uninteded behaviour where multiple psplash
binaries get installed (having the same priority for the psplash
symlink).

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>