linux-mainline: update to 6.15.

Author: Duncaen

srcpkgs/linux-mainline/template

@@ -1,6 +1,6 @@
 # Template file for 'linux-mainline'
 pkgname=linux-mainline
-version=6.14
+version=6.15
 revision=1
 build_style=meta
 depends="linux${version} linux-base"