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/drivers/fastboot/fb_nand.c b/drivers/fastboot/fb_nand.c
index b165468..eb8a36f 100644
--- a/drivers/fastboot/fb_nand.c
+++ b/drivers/fastboot/fb_nand.c
@@ -6,6 +6,7 @@
 
 #include <config.h>
 #include <common.h>
+#include <blk.h>
 #include <flash.h>
 
 #include <fastboot.h>