v2ray-geodata: make PKG_RELEASE numeric again

According to the documentation[1] 'PKG_RELEASE' should be a number,
so polulate the APK-style 'r' via 'VERSION' instead.

1. https://openwrt.org/docs/guide-developer/packages#buildpackage_variables

Fixes: 30796c59

 ("v2ray-geodata: use APK compatible version schema")
Reported-by: Sean Khan <datapronix@protonmail.com>
Signed-off-by: Tianling Shen <cnsztl@immortalwrt.org>