luv: remove the default value of the $(PKG)_SOURCE variable

Signed-off-by: Jerzy Grzegorek <jerzy.grzegorek@trzebnica.net>
Acked-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/luv/luv.mk

@@ -5,7 +5,6 @@
 ################################################################################
 
 LUV_VERSION = 1.7.4-4
-LUV_SOURCE = luv-$(LUV_VERSION).tar.gz
 LUV_SITE = https://github.com/luvit/luv/releases/download/$(LUV_VERSION)
 LUV_LICENSE = Apache-2.0
 LUV_LICENSE_FILES = LICENSE.txt