meta-google: image_types_hoth: fix hoth_secondary offset

Set the hoth_secondary offset to correct one.

Tested:
1. hoth fw can embed successfully & the size is correct.
2. BMC image can build and run.

Change-Id: I336d71d45349f0e58230a1175026ee4fad015733
Signed-off-by: Claire Liao <claireliao@google.com>
diff --git a/meta-google/classes/image_types_hoth.bbclass b/meta-google/classes/image_types_hoth.bbclass
index c2c6f73..f01ed90 100644
--- a/meta-google/classes/image_types_hoth.bbclass
+++ b/meta-google/classes/image_types_hoth.bbclass
@@ -25,7 +25,7 @@
         _append_image(os.path.join(d.getVar('DEPLOY_DIR_IMAGE', True),
                                'image-hoth-update-2nd'),
                   int(d.getVar('FLASH_HOTH_SECONDARY_OFFSET', True)),
-                  int(d.getVar('FLASH_SIZE', True)))
+                  int(d.getVar('FLASH_RWFS_OFFSET', True)))
 }
 do_generate_static[depends] += "virtual/hoth-firmware:do_deploy"
 do_generate_static[depends] += "${@'virtual/hoth-firmware-2nd:do_deploy' if ENABLE_HOTH_SECONDARY == 'yes' else ''}"