mox-support: there can not be empty install section in generic package

Fixes:
Makefile:93: WARNING: skipping mox-generic-support -- package has no install section
inconsistent: Package mox-support requires package mox-generic-support that is not available.

hardware/mox/mox-support/Makefile

@@ -48,6 +48,7 @@ endef
 Build/Compile:=:
 
 define Package/mox-generic-support/install
+	true
 endef
 
 define Package/mox-support/install