device-observatory: Add depend on vim to avoid build failure

/bin/sh: 2: xxd: not found
/bin/sh: 2: xxd: not found
Makefile:24: recipe for target 'src/files.h' failed
make[4]: *** [src/files.h] Error 127

Signed-off-by: Rosen Penev <rosenp@gmail.com>

utils/device-observatory/Makefile

@@ -2,14 +2,15 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=device-observatory
 PKG_VERSION:=1.2.0
-PKG_RELEASE:=2
-
-PKG_LICENSE:=GPL-3.0+
+PKG_RELEASE:=3
 
 PKG_SOURCE_URL:=https://codeload.github.com/mwarning/device-observatory/tar.gz/v$(PKG_VERSION)?
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_HASH:=83b3f362f154a427abbd3af31b3c2dda9983cdc15f6b833d804727ef0fbdc72e
 
+PKG_LICENSE:=GPL-3.0+
+PKG_BUILD_DEPENDS:=vim/host
+
 include $(INCLUDE_DIR)/package.mk
 
 define Package/device-observatory