site ci: obtain site-version from latest tag

Site-version had to be set in the past manually, even when tagging a
release. As this is not done every time, just parse it from the latest
tag on the history relative from the current commit.

This ensures the site- and firmware-version are always determined from
git tags when built from the CI.

Signed-off-by: David Bauer <[email protected]>
(cherry picked from commit ccf6015)

site.mk

@@ -1,4 +1,4 @@
-FFDA_SITE_VERSION := 3.0.3
+FFDA_SITE_VERSION := $(shell git describe --tags --abbrev=0 | sed 's/-.*//')
 
 DEFAULT_GLUON_RELEASE := $(FFDA_SITE_VERSION)~$(shell date '+%Y%m%d')
 DEFAULT_GLUON_PRIORITY := 0