uboot-envtools: use $(AUTORELEASE) for PKG_RELEASE

Use `$(AUTORELEASE)` variable rather than setting a PKG_RELEASE
on every commit manually.

Signed-off-by: Paul Spooren <[email protected]>

package/boot/uboot-envtools/Makefile

@@ -10,7 +10,7 @@ include $(TOPDIR)/rules.mk
 PKG_NAME:=uboot-envtools
 PKG_DISTNAME:=u-boot
 PKG_VERSION:=2020.04
-PKG_RELEASE:=20
+PKG_RELEASE:=$(AUTORELEASE)
 
 PKG_SOURCE:=$(PKG_DISTNAME)-$(PKG_VERSION).tar.bz2
 PKG_SOURCE_URL:= \