softoff: Fix the CI error

The CI for new patch set report errors in softoff code.

'''
../softoff/softoff.cpp: In member function 'int pldm::SoftPowerOff::getSensorInfo()':
../softoff/softoff.cpp:263:14: error: 'pdr' may be used uninitialized [-Werror=maybe-uninitialized]
  263 |         auto possibleStatesStart = pdr->possible_states;
      |              ^~~~~~~~~~~~~~~~~~~
../softoff/softoff.cpp:249:32: note: 'pdr' was declared here
  249 |         pldm_state_sensor_pdr* pdr;
cc1plus: all warnings being treated as errors
'''

Update code to fix that.

Signed-off-by: ThuBaNguyen <thu@os.amperecomputing.com>
Change-Id: Ib9df9f79978941ebad62164866cc688412a08922
diff --git a/softoff/softoff.cpp b/softoff/softoff.cpp
index a5c7a19..80abbf7 100644
--- a/softoff/softoff.cpp
+++ b/softoff/softoff.cpp
@@ -246,7 +246,7 @@
             return PLDM_ERROR;
         }
 
-        pldm_state_sensor_pdr* pdr;
+        pldm_state_sensor_pdr* pdr = nullptr;
         for (auto& rep : Response)
         {
             pdr = reinterpret_cast<pldm_state_sensor_pdr*>(rep.data());