treewide: replace AUTORELEASE with real PKG_RELEASE

Based on Paul Fertser <fercerpav@gmail.com>'s guidance:
Change AUTORELEASE in rules.mk to:
```
AUTORELEASE = $(if $(DUMP),0,$(shell sed -i "s/\$$(AUTORELEASE)/$(call commitcount,1)/" $(CURDIR)/Makefile))
```

then update all affected packages by:
```
for i in $(git grep -l PKG_RELEASE:=.*AUTORELEASE | sed 's^.*/\([^/]*\)/Makefile^\1^';);
do
	make package/$i/clean
done
```

Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>

package/boot/uboot-omap/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 include $(INCLUDE_DIR)/kernel.mk
 
 PKG_VERSION:=2021.07
-PKG_RELEASE:=$(AUTORELEASE)
+PKG_RELEASE:=21
 
 PKG_HASH:=312b7eeae44581d1362c3a3f02c28d806647756c82ba8c72241c7cdbe68ba77e