MIPS: ath79: Disable platform code for OF boards.

For OF boards we have to skip platform initialization code
so we can prove that OF code do all necessary initialization.

[ralf@linux-mips.org: Fix merge conflict.]

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Reviewed-by: Marek Vasut <marex@denx.de>
Cc: Alban Bedel <albeu@free.fr>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12877/
Patchwork: https://patchwork.linux-mips.org/patch/12920/


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