MIPS: add <dt-bindings/> symlink

MIPS: add <dt-bindings/> symlink

Add symlink to include/dt-bindings from arch/mips/boot/dts/include/ to
match the ones in ARM and Meta architectures so that preprocessed device
tree files can include various useful constant definitions.

See commit c58299a (kbuild: create an "include chroot" for DT bindings)
merged in v3.10-rc1 for details.

MIPS structures it's dts files a little differently to other
architectures, having a separate dts directory for each SoC/platform,
but most of the definitions in the dt-bindings/ directory are common so
for now lets just have a single "include chroot" for all MIPS platforms.

Signed-off-by: James Hogan <[email protected]>
Reviewed-by: Steven. J. Hill <[email protected]>
Cc: Michal Marek <[email protected]>
Cc: Shawn Guo <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Pawel Moll <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Acked-by: Stephen Warren <[email protected]>
Patchwork: http://patchwork.linux-mips.org/patch/5745/
Signed-off-by: Ralf Baechle <[email protected]>