fb_grub: support Fedora too for grub-install

Summary:
This is needed for ELN but should help if there's any non-EFI fedora
installs as well

Differential Revision: D55753946

fbshipit-source-id: 066ca67c63d41572b26eaf57f5bcdec69878f25a

cookbooks/fb_grub/recipes/packages.rb

@@ -30,7 +30,7 @@
   command lazy {
     cmd = value_for_platform_family(
       'debian' => 'grub-install',
-      'rhel' => 'grub2-install',
+      ['fedora', 'rhel'] => 'grub2-install',
     )
     # device of root-mount, strip off partition
     # note that this is a hack and it doesn't support properly dm devices