MIPS: Alchemy: Make 32kHz and r4k timer coexist peacefully

Now that the r4k timer is registered no matter what, bump the rating of
the Alchemy 32kHz timer so that it gets used when it is working,
and fall back on the r4k when it isn't.

This fixes a timer-related hang on platform with a working 32kHz timer
(the better rated c0 timer stops while executing 'wait' leading to (almost)
eternal sleep) and an oops on boot on platforms without a working 32kHz
timer (due to double registration of the r4k timer).

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc:  Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/4728/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>