csky/Kconfig: Add Kconfig.platforms to support some drivers

Such as snps,dw-apb-ictl

Signed-off-by: Guo Ren <[email protected]>
diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 00ac7bc..1c723cb 100644
--- a/arch/csky/Kconfig
+++ b/arch/csky/Kconfig
@@ -270,4 +270,6 @@
 	  Say N if you want to disable CPU hotplug.
 endmenu
 
+source "arch/csky/Kconfig.platforms"
+
 source "kernel/Kconfig.hz"