remove systemd-boot from hardware profiles (#307)

- We should not enable canTouchEfiVariables by default as this
  wears out the EFI storage.
- We should not set systemd-boot as default. This is up to the user to
  decide. There are exceptions when hardware only supports specific
  bootloaders so.

apple/macbook-pro/10-1/default.nix

@@ -6,10 +6,6 @@
     ../../../common/pc/laptop/ssd
   ];
 
-  # TODO: boot loader
-  boot.loader.systemd-boot.enable = true;
-  boot.loader.efi.canTouchEfiVariables = true;
-
   # TODO: reverse compat
   hardware.opengl.driSupport32Bit = true;