MIPS: ath79: make ath724x_pcibios_init visible for external code

Signed-off-by: René Bolldorf <xsecute@googlemail.com>
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/3487/


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