rename tried_fwb constants

Change-Id: Ib8018bfe29eed50766c699d832efe4f1afcabb1a

BUG=none
TEST=make && make runtests

Review URL: http://codereview.chromium.org/6597015
diff --git a/host/lib/crossystem.c b/host/lib/crossystem.c
index da9d80b..9fe1feb 100644
--- a/host/lib/crossystem.c
+++ b/host/lib/crossystem.c
@@ -486,7 +486,7 @@
   }
   /* NV storage values with no defaults for older BIOS. */
   else if (!strcasecmp(name,"tried_fwb")) {
-    value = VbGetNvStorage(VBNV_FW_USED_TRY_B);
+    value = VbGetNvStorage(VBNV_TRIED_FIRMWARE_B);
   }
   /* NV storage values.  If unable to get from NV storage, fall back to the
    * CMOS reboot field used by older BIOS. */