include: remove now unused PACKAGE_SUBDIR variable

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

include/package-dumpinfo.mk

@@ -52,7 +52,6 @@ $(if $(PKG_LICENSE),License: $(PKG_LICENSE)
 $(if $(KCONFIG),Kernel-Config: $(KCONFIG)
 )$(if $(BUILDONLY),Build-Only: $(BUILDONLY)
 )$(if $(HIDDEN),Hidden: $(HIDDEN)
-)$(if $(PACKAGE_SUBDIR),Package-Subdir: $(PACKAGE_SUBDIR)
 )Description: $(if $(Package/$(1)/description),$(Package/$(1)/description),$(TITLE))
 $(if $(URL),$(URL)
 )$(MAINTAINER)