powerpc/ps3: Mark ps3_setup_uhc_device() __init

ps3_setup_uhc_device() is only called from ps3_setup_ehci_device() and
ps3_setup_ohci_device(), which are both marked __init.  Hence replace
the former's __ref marker by __init.

Note that before commit bd721ea7 ("treewide: replace obsolete
_refok by __ref"), the function was marked __init_refok, which probably
should have been __init in the first place.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://patch.msgid.link/31fe9435056fcfbf82c3a01693be278d5ce4ad0f.1730899557.git.geert+renesas@glider.be