tgt: depend on @KERNEL_AIO and @KERNEL_DIRECT_IO instead of modifying the global kernel config

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

net/tgt/Makefile

@@ -30,7 +30,7 @@ define Package/tgt
   CATEGORY:=Network
   URL:=http://stgt.sourceforge.net/
   TITLE:=userspace iSCSI target
-  DEPENDS:=+libpthread +libaio +@KERNEL_AIO +@KERNEL_DIRECT_IO
+  DEPENDS:=+libpthread +libaio @KERNEL_AIO @KERNEL_DIRECT_IO
 endef
 
 define Package/tgt/description