dell/xps/13-9380: init (#97)

This is pretty much a copy of XPS 9370, without kaby-laky and the throttle bug. I was getting lockups with the kaby-laky changes and the throttle bug did not seem to have an impact either way.

dell/xps/13-9380/README.wiki

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+= Dell XPS 13 9380 =
+
+== Battery drain when sleeping ==
+
+The laptop uses the S2 sleep mode by default instead of S3, which leads to
+draining a lot of battery during sleep.
+
+See https://wiki.archlinux.org/index.php/Dell_XPS_13_(9370)#Power_Management
+and https://bugzilla.kernel.org/show_bug.cgi?id=199689#c3 for reference

dell/xps/13-9380/default.nix

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+{ lib, pkgs, ... }:
+
+{
+  imports = [
+    ../../../common/pc/laptop
+    ../../../common/pc/laptop/acpi_call.nix
+  ];
+
+  # Force S3 sleep mode. See README.wiki for details.
+  boot.kernelParams = [ "mem_sleep_default=deep" ];
+
+  # touchpad goes over i2c
+  boot.blacklistedKernelModules = [ "psmouse" ];
+}