linux-rt: use latest version

Take the last kernel version listed in sha256sums.asc when
multiple versions are listed.
We assume that the patches listed in sha256sums.asc are ordered by
increasing version number.

pkgs/os-specific/linux/kernel/update-rt.sh

@@ -36,7 +36,8 @@ file-version() {
 latest-rt-version() {
     branch="$1" # e.g. 5.4
     curl -sL "$mirror/projects/rt/$branch/sha256sums.asc" |
-        sed -ne '/.patch.xz/ { s/.*patch-\(.*\).patch.xz/\1/; p; q }'
+        sed -ne '/.patch.xz/ { s/.*patch-\(.*\).patch.xz/\1/p}' |
+        tail -n 1
 }
 
 update-if-needed() {