linux-firmware: bump to 20230919

Bump linux-firmware to a tagged version again.

Change-Id: I65fcce7ed3ce0323e1504d339b349fc3a901bff7
Reviewed-on: https://review.monogon.dev/c/monogon/+/2209
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
Tested-by: Jenkins CI
diff --git a/WORKSPACE b/WORKSPACE
index 51e10da..a2c972a 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -200,7 +200,7 @@
 
 linux_firmware_external(
     name = "linux-firmware",
-    version = "f2eb058afc57348cde66852272d6bf11da1eef8f",
+    version = "20230919",
 )
 
 load("//third_party/intel_ucode:external.bzl", "intel_ucode_external")