Append '\0' with generated Intel SAR content

Firmware expects a null-terminated string therefore adding extra
`\0` to termitate the sar string.

BUG=b:178302811
TEST=gen_config

Change-Id: I4c7d4a1aca2734f913ae922ce3758fed3afbe6b7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/config/+/2742358
Commit-Queue: Andrew Lamb <andrewlamb@chromium.org>
Reviewed-by: Andrew Lamb <andrewlamb@chromium.org>
(cherry picked from commit 89cddaafffb0523e00e650db9401dcf1c76d0ec0)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/config/+/2793082
Reviewed-by: YH Lin <yueherngl@chromium.org>
Commit-Queue: YH Lin <yueherngl@chromium.org>
diff --git a/payload_utils/cros_config_proto_converter.py b/payload_utils/cros_config_proto_converter.py
index 039c9bf..67bde49 100755
--- a/payload_utils/cros_config_proto_converter.py
+++ b/payload_utils/cros_config_proto_converter.py
@@ -1333,7 +1333,7 @@
           wgds_value(intel_config.wgds_version) +
           offset_table(intel_config.offset_fcc) +
           offset_table(intel_config.offset_eu) +
-          offset_table(intel_config.offset_other))
+          offset_table(intel_config.offset_other) + '\0')
 
 
 def Main(project_configs, program_config, output):  # pylint: disable=invalid-name
diff --git a/test/project/fake/fake/sw_build_config/platform/chromeos-config/generated/wifi/wifi_sar_6.hex b/test/project/fake/fake/sw_build_config/platform/chromeos-config/generated/wifi/wifi_sar_6.hex
index cc35f53..5276836 100644
--- a/test/project/fake/fake/sw_build_config/platform/chromeos-config/generated/wifi/wifi_sar_6.hex
+++ b/test/project/fake/fake/sw_build_config/platform/chromeos-config/generated/wifi/wifi_sar_6.hex
Binary files differ