Slightly improve raw_remove()/udp_remove() implementation

There should be no duplicate pcb in raw_pcbs/udp_pcbs list.
So the implementation of raw_remove()/udp_remove() can break from the for
loop once the target pcb is found and removed from the list.

Signed-off-by: Axel Lin <axel.lin@ingics.com>

src/core/raw.c

@@ -383,6 +383,7 @@ raw_remove(struct raw_pcb *pcb)
       if (pcb2->next != NULL && pcb2->next == pcb) {
         /* remove pcb from list */
         pcb2->next = pcb->next;
+        break;
       }
     }
   }

src/core/udp.c

@@ -1131,6 +1131,7 @@ udp_remove(struct udp_pcb *pcb)
       if (pcb2->next != NULL && pcb2->next == pcb) {
         /* remove pcb from list */
         pcb2->next = pcb->next;
+        break;
       }
     }
   }