anaconda: don't force non-encrypted /boot on coreboot systems

With grub payload it is possible to have all the partitions encrypted.

Based on patch by @tlaurion

Fixes QubesOS/qubes-issues#2118

pyanaconda/bootloader.py

@@ -43,6 +43,8 @@
 from pyanaconda.i18n import _, N_
 
 import logging
+import subprocess
+
 log = logging.getLogger("anaconda")
 
 class serial_opts(object):
@@ -1414,12 +1416,11 @@ class GRUB2(GRUB):
     # XXX we probably need special handling for raid stage1 w/ gpt disklabel
     #     since it's unlikely there'll be a bios boot partition on each disk
 
-    @property
-    def stage2_format_types(self):
-        if productName.startswith("Red Hat "):              # pylint: disable=no-member
-            return ["xfs", "ext4", "ext3", "ext2", "btrfs"]
-        else:
-            return ["ext4", "ext3", "ext2", "btrfs", "xfs"]
+    stage2_format_types = ["ext4", "ext3", "ext2", "btrfs", "xfs"]
+
+    encryption_support = True
+    stage2_format_types += ["lvmlv"]
+    skip_bootloader = flags.cmdline.getbool("skip_grub", False)
 
     #
     # grub-related conveniences