MIPS: AR7: Remove 'space before tabs' in platform.c

Signed-off-by: Florian Fainelli <florian@openwrt.org>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2490/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>