linux_{5_1,testing}: enable kernel fpu functions

same motivation as in 7b77c27caa

pkgs/top-level/all-packages.nix

@@ -15145,6 +15145,7 @@ in
     kernelPatches =
       [ kernelPatches.bridge_stp_helper
         kernelPatches.modinst_arg_list_too_long
+        kernelPatches.export_kernel_fpu_functions
       ];
   };
 
@@ -15152,6 +15153,7 @@ in
     kernelPatches = [
       kernelPatches.bridge_stp_helper
       kernelPatches.modinst_arg_list_too_long
+      kernelPatches.export_kernel_fpu_functions
     ];
   };