sh: Migrate common board headers to mach-common/.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/Makefile b/arch/sh/Makefile
index 0bc9560..1f409bf 100644
--- a/arch/sh/Makefile
+++ b/arch/sh/Makefile
@@ -125,6 +125,9 @@
 	     $(filter-out ., $(patsubst %,%/,$(machdir-y))))
 endif
 
+# Common machine type headers. Not part of the arch/sh/boards/ hierarchy.
+machdir-y	+= mach-common
+
 # Companion chips
 core-$(CONFIG_HD6446X_SERIES)	+= arch/sh/cchips/hd6446x/