cli: dereferencing null coverity fix

CID: 1124489

https://scan6.coverity.com/reports.htm#v42375/p10714/fileInstanceId=85018660&defectInstanceId=25877775&mergedDefectId=577602

updates: bz#789278
Change-Id: I0ebfbc52ecd5e3b70574df5f286116f872514cc6
Signed-off-by: Sanju Rakonde <srakonde@redhat.com>

cli/src/cli-cmd-parser.c

@@ -3216,7 +3216,7 @@ cli_cmd_volume_top_parse (const char **words, int wordcount,
                 key = (char *) words[index];
                 value = (char *) words[index+1];
 
-                if ( key && !value ) {
+                if (!key || !value) {
                         ret = -1;
                         goto out;
                 }