WORKSPACE: bump Linux to 5.15.2

This involves ripping out fsinfo because there now is quotactl_fd which
handles what we originally used fsinfo for. I also enabled a few new
interesting kernel features in the config like the Landlock LSM and
KFENCE.

Change-Id: Ic0a113893a437b2c8068d06984fdc386f34e6adb
Reviewed-on: https://review.monogon.dev/c/monogon/+/444
Reviewed-by: Sergiusz Bazanski <serge@monogon.tech>
diff --git a/metropolis/pkg/fsquota/BUILD.bazel b/metropolis/pkg/fsquota/BUILD.bazel
index dbeb19b..b25d812 100644
--- a/metropolis/pkg/fsquota/BUILD.bazel
+++ b/metropolis/pkg/fsquota/BUILD.bazel
@@ -3,10 +3,7 @@
 
 go_library(
     name = "go_default_library",
-    srcs = [
-        "fsinfo.go",
-        "fsquota.go",
-    ],
+    srcs = ["fsquota.go"],
     importpath = "source.monogon.dev/metropolis/pkg/fsquota",
     visibility = ["//metropolis:__subpackages__"],
     deps = [