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/fs/fs_internal.c b/fs/fs_internal.c
index 1ff804d..115c010 100644
--- a/fs/fs_internal.c
+++ b/fs/fs_internal.c
@@ -6,6 +6,7 @@
  */
 
 #include <common.h>
+#include <blk.h>
 #include <compiler.h>
 #include <part.h>
 #include <memalign.h>