osbase/build: move efi.bzl, split and move def.bzl to their corresponding action

This is a small reorganization to make the osbase/build less dependent on each other.

Change-Id: I8c12f04f3bdc98128c5424f142f452c2e094f2e8
Reviewed-on: https://review.monogon.dev/c/monogon/+/3903
Tested-by: Jenkins CI
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/osbase/build/fwprune/def.bzl b/osbase/build/fwprune/def.bzl
index 4633c93..e05d237 100644
--- a/osbase/build/fwprune/def.bzl
+++ b/osbase/build/fwprune/def.bzl
@@ -1,4 +1,4 @@
-load("//osbase/build:def.bzl", "FSSpecInfo")
+load("//osbase/build/fsspec:def.bzl", "FSSpecInfo")
 
 def _fsspec_linux_firmware(ctx):
     fsspec_out = ctx.actions.declare_file(ctx.label.name + ".prototxt")