secril-client: return exact error code from blockingWrite()

Change-Id: Ibb6d3636648480c53a2fd19044eefe5b97f1eceb

ril/libsecril-client/secril-client.cpp

@@ -1572,9 +1572,8 @@ static int blockingWrite(int fd, const void *buffer, size_t len) {
         }
         else {
             RLOGE ("RIL Response: unexpected error on write errno:%d", errno);
-            printf("RIL Response: unexpected error on write errno:%d\n", errno);
             close(fd);
-            return -1;
+            return -errno;
         }
     }