ipxe: correct licensing information

Updates the licensing information to match Fedora's SPDX
identifier. This is necessary because of IPXE's built-in EFI
headers and other third-party code embedded in IPXE. Please
note that Nixpkgs does not yet have a way to programatically
identify `GPL-2.0-or-later WITH UBDL-exception` or the `AND`
and `OR` logical identifiers in SPDX, so the best we can do
is express all of the licenses in a list and add a comment
for UBDL.

Reported-by: sanana <umutinanerdogan@pm.me>
Signed-off-by: Fernando Rodrigues <alpha@sigmasquadron.net>

pkgs/by-name/ip/ipxe/package.nix

@@ -142,7 +142,15 @@ stdenv.mkDerivation (finalAttrs: {
   meta = {
     description = "Network boot firmware";
     homepage = "https://ipxe.org/";
-    license = lib.licenses.gpl2Only;
+    license = with lib.licenses; [
+      bsd2
+      bsd3
+      gpl2Only
+      gpl2UBDLPlus
+      isc
+      mit
+      mpl11
+    ];
     platforms = lib.platforms.linux;
     maintainers = with lib.maintainers; [ sigmasquadron ];
   };