MIPS: Clean up linker script using new linker script macros.

This patch results in fewer output sections and in some data being
reordered, but should have no functional impact.

Signed-off-by: Nelson Elhage <nelhage@ksplice.com>
Signed-off-by: Tim Abbott <tabbott@ksplice.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>