nixos/amazon: move nvme_core.io_timeout to runtime module

This kernel parameter was accidentally added to the image builder module
in 2018 (e4777ae2d8) when it should have been in the runtime config.
This causes a mismatch between AMIs built with the builder and systems
configured with just the runtime module.

Move it to modules/virtualisation/amazon-image.nix so that all EC2
instances get the recommended NVMe timeout, regardless of how they
were provisioned.

nixos/maintainers/scripts/ec2/amazon-image.nix

@@ -11,7 +11,6 @@ let
     mkOption
     optionalString
     types
-    versionAtLeast
     ;
   inherit (lib.options) literalExpression;
   cfg = config.amazonImage;
@@ -46,16 +45,6 @@ in
     })
   ];
 
-  # Amazon recommends setting this to the highest possible value for a good EBS
-  # experience, which prior to 4.15 was 255.
-  # https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html#timeout-nvme-ebs-volumes
-  config.boot.kernelParams =
-    let
-      timeout =
-        if versionAtLeast config.boot.kernelPackages.kernel.version "4.15" then "4294967295" else "255";
-    in
-    [ "nvme_core.io_timeout=${timeout}" ];
-
   options.amazonImage = {
     contents = mkOption {
       example = literalExpression ''

nixos/modules/virtualisation/amazon-image.nix

@@ -59,10 +59,19 @@ in
     ];
     boot.initrd.kernelModules = [ "xen-blkfront" ];
     boot.initrd.availableKernelModules = [ "nvme" ];
-    boot.kernelParams = [
-      "console=ttyS0,115200n8"
-      "random.trust_cpu=on"
-    ];
+    boot.kernelParams =
+      let
+        # Amazon recommends setting this to the highest possible value for a good EBS
+        # experience, which prior to 4.15 was 255.
+        # https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html#timeout-nvme-ebs-volumes
+        nvmeTimeout =
+          if lib.versionAtLeast config.boot.kernelPackages.kernel.version "4.15" then "4294967295" else "255";
+      in
+      [
+        "console=ttyS0,115200n8"
+        "random.trust_cpu=on"
+        "nvme_core.io_timeout=${nvmeTimeout}"
+      ];
 
     # Prevent the nouveau kernel module from being loaded, as it
     # interferes with the nvidia/nvidia-uvm modules needed for CUDA.