Move to sysmocom poky repository

we needed to patch bitbake to make the git fetcher use https by default
in order to still be able to fetch from github repositories.  This means
we cannot continue to use upstreak poky but must use a private fork.

Makefile

@@ -93,7 +93,7 @@ git:
 
 ## Clone repositories. The other option is by variable something like BRNACH_poky, REPO_poky
 git/poky: | git
-	$(V)cd git && git clone --branch=$(GIT_BRANCH_POKY) --depth=1 https://git.yoctoproject.org/poky
+	$(V)cd git && git clone --branch=$(GIT_BRANCH_POKY) --depth=1 https://gitea.sysmocom.de/sysmo-bts/generic-poky poky
 git/meta-sysmocom-bsp: | git
 	cd git && git clone --branch=$(GIT_BRANCH_SYSMOCOM_BSP) https://gitea.sysmocom.de/sysmo-bts/meta-sysmocom-bsp
 git/meta-telephony: | git