MIPS: IP22, IP28: Migrate to new platform makefile style.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kbuild.platforms b/arch/mips/Kbuild.platforms
index e391b6d..acc3dc8 100644
--- a/arch/mips/Kbuild.platforms
+++ b/arch/mips/Kbuild.platforms
@@ -8,6 +8,7 @@
 platforms += loongson
 platforms += mipssim
 platforms += pmc-sierra
+platforms += sgi-ip22
 platforms += sgi-ip27
 platforms += sni
 platforms += vr41xx