cros_bundle_firmware: drop --force-rw option

It was only effective if fmap.dts pre-configured the firmware to choose
the read-only path, which only a small number of ancient boards did.

BUG=none
TEST=none
CQ-DEPEND=CL:371179

Change-Id: I67e7a6cdfb712bfb29cfff0545081d7d0113def6
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://chromium-review.googlesource.com/371280
Commit-Ready: Patrick Georgi <pgeorgi@chromium.org>
Tested-by: Patrick Georgi <pgeorgi@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
diff --git a/host/lib/bundle_firmware.py b/host/lib/bundle_firmware.py
index 82350fa..e58dd3e 100644
--- a/host/lib/bundle_firmware.py
+++ b/host/lib/bundle_firmware.py
@@ -107,7 +107,6 @@
     # Set up the things we need to know in order to operate.
     self._board = None          # Board name, e.g. nyan.
     self._fdt_fname = None      # Filename of our FDT.
-    self._force_rw = None
     self._force_efs = None
     self._gbb_flags = None
     self._keydir = None
@@ -183,7 +182,7 @@
     self.cbfs_files = cbfs_files
     self.rocbfs_files = rocbfs_files
 
-  def SetOptions(self, small, gbb_flags, force_rw=False, force_efs=False):
+  def SetOptions(self, small, gbb_flags, force_efs=False):
     """Set up options supported by Bundle.
 
     Args:
@@ -191,13 +190,11 @@
           firmware image. This is useful for devs who want to replace just the
           U-Boot part while keeping the keys, gbb, etc. the same.
       gbb_flags: Specification for string containing adjustments to make.
-      force_rw: Force firmware into RW mode.
       force_efs: Force firmware to use 'early firmware selection' feature,
           where RW firmware is selected before SDRAM is initialized.
     """
     self._small = small
     self._gbb_flags = gbb_flags
-    self._force_rw = force_rw
     self._force_efs = force_efs
 
   def _GetBuildRoot(self):
@@ -1004,9 +1001,6 @@
     self._out.Notice("Model: %s" % fdt.GetString('/', 'model'))
 
     pack = PackFirmware(self._tools, self._out)
-    if self._force_rw:
-      fdt.PutInteger('/flash/rw-a-vblock', 'preamble-flags', 0)
-      fdt.PutInteger('/flash/rw-b-vblock', 'preamble-flags', 0)
     if self._force_efs:
       fdt.PutInteger('/chromeos-config', 'early-firmware-selection', 1)
     pack.use_efs = fdt.GetInt('/chromeos-config', 'early-firmware-selection',