autorandr: add crtc option

This option was missing. It is generated by autorandr when executing
`autorandr --save my_profile`.

Fixes #1024
PR #1283

tests/modules/programs/autorandr/basic-configuration.conf

@@ -3,6 +3,7 @@ off
 
 output DP2
 pos 0x0
+crtc 0
 primary
 mode 1920x1080
 transform 0.600000,0.000000,0.000000,0.000000,0.600000,0.000000,0.000000,0.000000,1.000000

tests/modules/programs/autorandr/basic-configuration.nix

@@ -13,6 +13,7 @@
           config = {
             DP1.enable = false;
             DP2 = {
+              crtc = 0;
               primary = true;
               position = "0x0";
               mode = "1920x1080";