While applying commit 9909bc43 ("dt-bindings: MIPS: Document Ingenic
 SoCs binding.") I've messed up by "fixing" indentation in a C style,
which is wrong for yaml files. Replace tabs back to spaces.

Fixes: 9909bc43 ("dt-bindings: MIPS: Document Ingenic SoCs binding.")
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>