mips: bmips: init clocks earlier

device_initcall() is too late for bcm63xx.
We need to call of_clk_init() earlier in order to properly boot.

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>