add tftpboot test for mips

pkgs/kernel/default.nix

@@ -51,6 +51,7 @@ stdenv.mkDerivation rec {
   patches = [
     ./cmdline-cookie.patch
     ./phram-allow-cached-mappings.patch
+    ./mips-malta-fdt-from-bootloader.patch
   ];
 
   # this is here to work around what I think is a bug in nixpkgs

pkgs/kernel/mips-malta-fdt-from-bootloader.patch

@@ -0,0 +1,18 @@
+diff --git a/arch/mips/mti-malta/malta-setup.c b/arch/mips/mti-malta/malta-setup.c
+index 21cb3ac1237b..f11409ae9583 100644
+--- a/arch/mips/mti-malta/malta-setup.c
++++ b/arch/mips/mti-malta/malta-setup.c
+@@ -192,7 +192,12 @@ static void __init bonito_quirks_setup(void)
+ 
+ void __init *plat_get_fdt(void)
+ {
+-	return (void *)__dtb_start;
++    void *r=0;
++    if(fw_arg0 == -2)
++	r = (void *) KSEG1ADDR(fw_arg1);
++    else
++	r = (void *)  __dtb_start;
++    return r;
+ }
+ 
+ void __init plat_mem_setup(void)