[MIPS] Malta: use tabs not spaces

This patch fixes all "use tabs not spaces" warnings reported by
the checkpatch.pl script on the board-specific files.

No functional changes introduced.

Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>