common: Drop part.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/dm/blk.c b/test/dm/blk.c
index 9c71adc..94b2855 100644
--- a/test/dm/blk.c
+++ b/test/dm/blk.c
@@ -5,6 +5,7 @@
 
 #include <common.h>
 #include <dm.h>
+#include <part.h>
 #include <usb.h>
 #include <asm/state.h>
 #include <dm/test.h>