MT#57501 'max_per' may be used uninitialized

Fix for:

     doCPLC.c: In function 'doThePLC':
     doCPLC.c:261:29: warning: 'max_per' may be used uninitialized [-Wmaybe-uninitialized]
       261 |            iLBCdec_inst->per=max_per;
           |            ~~~~~~~~~~~~~~~~~^~~~~~~~
     doCPLC.c:93:42: note: 'max_per' declared here
        93 |        float gain_comp, maxcc_comp, per, max_per;
           |                                          ^~~~~~~

Change-Id: I7af6e280836d3cbbc8860c2c5b9a732f658ccc40

core/plug-in/ilbc/iLBC_rfc3951/doCPLC.c

@@ -256,7 +256,7 @@
 
        /* update state */
 
-       if (PLI) {
+       if (PLI == 1) {
            iLBCdec_inst->prevLag = lag;
            iLBCdec_inst->per=max_per;
        }