bmc-state-manager: revise BMC reboot cause

According new design from below commit:
https://gerrit.openbmc.org/c/openbmc/docs/+/73678

We need to revise `RebootCause` value as below:

`WDIOF_EXTERN1`   => `RebootCause::Software`
`WDIOF_CARDRESET` => `RebootCause::Watchdog`

Tested:
busctl get-property xyz.openbmc_project.State.BMC \
/xyz/openbmc_project/state/bmc0 xyz.openbmc_project.State.BMC \
LastRebootCause

When unplug/plug in BMC power cable then return as below:
s "xyz.openbmc_project.State.BMC.BMCResetCause.POR"

When executing reboot command then return as below:
s "xyz.openbmc_project.State.BMC.BMCResetCause.Software"

When kernel panic watchdog be triggered then return as below:
s "xyz.openbmc_project.State.BMC.BMCResetCause.Watchdog"

Signed-off-by: Tim Lee <timlee660101@gmail.com>
Change-Id: Iba7dfe6822d5f2f595c19e77aa559bb3b0a9d69c
diff --git a/bmc_state_manager.cpp b/bmc_state_manager.cpp
index c891376..5376994 100644
--- a/bmc_state_manager.cpp
+++ b/bmc_state_manager.cpp
@@ -288,13 +288,13 @@
     switch (bootReason)
     {
         case WDIOF_EXTERN1:
-            this->lastRebootCause(RebootCause::Watchdog);
+            this->lastRebootCause(RebootCause::Software);
             return;
         case WDIOF_CARDRESET:
-            this->lastRebootCause(RebootCause::POR);
+            this->lastRebootCause(RebootCause::Watchdog);
             return;
         default:
-            this->lastRebootCause(RebootCause::Unknown);
+            this->lastRebootCause(RebootCause::POR);
             // Continue below to see if more details can be found
             // on reason for reboot
             break;