MIPS: Alchemy: DB1200: Remove custom wait implementation

While playing with the out-of-tree MAE driver module, the system would
panic after a while in the db1200 custom wait code after wakeup due to
a clobbered k0 register being used as target address of a store op.

Remove the custom wait implementation and revert back to the Alchemy-
recommended implementation already set as default.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
To: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/1092/


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