update_engine: Fix TPM variable name max_kernel_rollfoward

- In a previous CL I named the variable incorrectly

BUG=chromium:814090
TEST=FEATURES=test emerge-samus update_engine

Change-Id: I17cbc85d42ba03040bfdae436cedd0238698b47e
Reviewed-on: https://chromium-review.googlesource.com/1059944
Commit-Ready: Zentaro Kavanagh <zentaro@chromium.org>
Tested-by: Zentaro Kavanagh <zentaro@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/hardware_chromeos.cc b/hardware_chromeos.cc
index 3099151..c0f2b67 100644
--- a/hardware_chromeos.cc
+++ b/hardware_chromeos.cc
@@ -190,9 +190,9 @@
   return VbGetSystemPropertyInt("tpm_fwver");
 }
 
-bool HardwareChromeOS::SetMaxKernelKeyRollforward(int max_kernel_rollforward) {
-  return VbSetSystemPropertyInt("max_kernel_rollforward",
-                                max_kernel_rollforward) == 0;
+bool HardwareChromeOS::SetMaxKernelKeyRollforward(int kernel_max_rollforward) {
+  return VbSetSystemPropertyInt("kernel_max_rollforward",
+                                kernel_max_rollforward) == 0;
 }
 
 int HardwareChromeOS::GetPowerwashCount() const {