MIPS: BCM47XX: fix position of cpu_wait disabling

The disabling of cpu_wait was done too early, before the detection was
done. This moves the code to a position where it actually works.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Acked-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6352/