common: build.sh: fix recovery depend on kernel image

Make sure that the target of build_recovery use correct
kernel image.

Change-Id: I993cb66a61da945123f5fbcabde87b1999a7af4e
Signed-off-by: Weiwen Chen <cww@rock-chips.com>

common/build.sh

@@ -266,6 +266,7 @@ elif [ $BUILD_TARGET == buildroot ];then
     build_buildroot
     exit 0
 elif [ $BUILD_TARGET == recovery ];then
+    build_kernel
     build_recovery
     exit 0
 elif [ $BUILD_TARGET == ramboot ];then