ARM: brcmstb: Setup BIU control registers during boot

Call brcmstb_biuctrl_init() in brcmstb's init_irq machine descriptor
callback since we need to setup the Bus Interface Unit before SMP in
particular, but we also need to be able to remap registers.

Acked-by: Gregory Fong <gregory.0xf0@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>