[MIPS] Remove unused system type name for DDB5074 and DDB5476.

This patch removes unused system type name.
DDB5074 and DDB5476 were already removed.

Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
1 file changed