nvidia-x11: stable 387.34 -> 390.25

390.x is Nvidia's latest "Long Lived Branch version" according to
https://www.nvidia.com/object/unix.html so this upgrades the stable version
from 387.xx.

390.x also also has support for kernel 4.15 and later (due to removal of the
old init_timer APIs, among other things), meaning that
linuxPackages_4_15.nvidia_x11 now builds correctly.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

pkgs/os-specific/linux/nvidia-x11/default.nix

@@ -17,11 +17,11 @@ in
 {
   # Policy: use the highest stable version as the default (on our master).
   stable = generic {
-    version = "387.34";
-    sha256_32bit = "1haqk5h1fcmwp7kn9644k280wn409kh0xbivrj1ks8r8f4nbvfmq";
-    sha256_64bit = "06w8dw6hb40ymz6ax7v82j29ihmp3d7yxsi8ah9ch10jldl973z4";
-    settingsSha256 = "0dpm22ggpr93ypz24ap9vgx43ik7lw6cxcb29v8ys2iinhs7zm7s";
-    persistencedSha256 = "02lf9b6j85amc1vr84lj98q74a680nrx4fmpxj17cz597yq8s200";
+    version = "390.25";
+    sha256_32bit = "0fkbpx01l46pprrd4nlc2y6hfmkb55ddlwm1r84kr6j08qmmb0qi";
+    sha256_64bit = "0whsls1mm6vkll5qmxnyz8vjgspp1rmqpsampgi83k62n514c08r";
+    settingsSha256 = "1jhbr68z36s3fr9vx3ga2f6yrzlwpc0j5mw8h12g65p7wdsbk6y7";
+    persistencedSha256 = "033azbhi50f1b0lw759sncgf7ckh2m2c0khj5v15sch9kl1fzk8i";
   };
 
   beta = generic {