v4l2loopback: update version following PR comment

Signed-off-by: Michel Promonet <michel.promonet@free.fr>

kernel/v4l2loopback/Makefile

@@ -9,14 +9,13 @@ include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/kernel.mk
 
 PKG_NAME:=v4l2loopback
-PKG_VERSION:=master
 PKG_RELEASE:=$(AUTORELEASE)
 
 PKG_SOURCE_PROTO:=git
-PKG_SOURCE_URL:=https://github.com/umlaeute/v4l2loopback
+PKG_SOURCE_URL:=https://github.com/umlaeute/v4l2loopback.git
 PKG_SOURCE_VERSION:=baf9de279afc7a7c7513e9c40a0c9ff88f456af4
-PKG_MIRROR_HASH:=ff834e16b13e9b38814095d95ab033ea7eae075689956e227f157e95bc075983
-
+PKG_SOURCE_DATE:=2021-07-13
+PKG_MIRROR_HASH:=811a4b0bbefe14cf4a74dbb3d45f5ae147f50f1d67dbb6f0fe3e5a9888adf49a
 
 PKG_MAINTAINER:=Michel Promonet <michel.promonet@free.fr>