Fix interval type in STATE_REG_HOLD_OFF for overdue registrations

Updated `interval` type from `time_t` to `int32_t` in registration.c
to correctly handle negative differences when currentTime exceeds
targetP->registration. This fixes a bug where unsigned `time_t`
caused large positive intervals, delaying registrations.
The change ensures compliance with LwM2M registration timing requirements.

Signed-off-by: CMT-Ashish <[email protected]>

Author: ashishmac7

core/registration.c

@@ -2069,7 +2069,7 @@ void registration_step(lwm2m_context_t * contextP,
 #ifndef LWM2M_VERSION_1_0
         case STATE_REG_HOLD_OFF:
         {
-            time_t interval = targetP->registration - currentTime;
+            int32_t interval = targetP->registration - currentTime;
             if (0 >= interval)
             {
                 prv_register(contextP, targetP);