MIPS: RB532: 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 8a8f99b..61f150b 100644
--- a/arch/mips/Kbuild.platforms
+++ b/arch/mips/Kbuild.platforms
@@ -9,6 +9,7 @@
 platforms += mipssim
 platforms += mti-malta
 platforms += pmc-sierra
+platforms += rb532
 platforms += sgi-ip22
 platforms += sgi-ip27
 platforms += sgi-ip32