Don't cache config location in the DPM code

Now that we cache the configuration location in the configuration code
itself, we don't need to cache it elsewhere.  This makes the DPM code
for evaluating Type-C Current much cleaner.

src/device_policy_manager.c

 
 bool pdb_dpm_evaluate_typec_current(void)
 {
-    static struct pdb_config *cfg = NULL;
-
-    /* Get the configuration the first time this function runs, and again any
-     * time the status is found to not be valid. */
-    if (cfg == NULL || cfg->status != PDB_CONFIG_STATUS_VALID) {
-        cfg = pdb_config_flash_read();
-    }
+    struct pdb_config *cfg = pdb_config_flash_read();
 
     /* We don't control the voltage anymore; it will always be 5 V. */
     dpm_requested_voltage = PD_MV2PDV(5000);