uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

pkgs/os-specific/linux/freefall/default.nix

@@ -0,0 +1,33 @@
+{ lib, stdenv, kernel }:
+
+stdenv.mkDerivation {
+  inherit (kernel) version src;
+
+  pname = "freefall";
+
+  postPatch = ''
+    cd tools/laptop/freefall
+
+    # Default time-out is a little low, probably because the AC/lid status
+    # functions were never implemented. Because no-one still uses HDDs, right?
+    substituteInPlace freefall.c --replace "alarm(2)" "alarm(5)"
+  '';
+
+  makeFlags = [ "PREFIX=$(out)" ];
+
+  meta = with lib; {
+    inherit (kernel.meta) homepage license;
+
+    description = "Free-fall protection for spinning HP/Dell laptop hard drives";
+    longDescription = ''
+      Provides a shock protection facility in modern laptops with spinning hard
+      drives, by stopping all input/output operations on the internal hard drive
+      and parking its heads on the ramp when critical situations are anticipated.
+      Requires support for the ATA/ATAPI-7 IDLE IMMEDIATE command with unload
+      feature, which should cause the drive to switch to idle mode and unload the
+      disk heads, and an accelerometer device. It has no effect on SSD devices!
+    '';
+
+    platforms = platforms.linux;
+  };
+}