[undi] Apply quota only to number of complete received packets

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/arch/i386/drivers/net/undinet.c

 /** Delay between retries of PXENV_UNDI_INITIALIZE */
 #define UNDI_INITIALIZE_RETRY_DELAY_MS 200
 
-/** Maximum number of calls to PXENV_UNDI_ISR per poll */
-#define UNDI_POLL_QUOTA 4
+/** Maximum number of received packets per poll */
+#define UNDI_RX_QUOTA 4
 
 /** Alignment of received frame payload */
 #define UNDI_RX_ALIGN 16
 	struct undi_nic *undinic = netdev->priv;
 	struct s_PXENV_UNDI_ISR undi_isr;
 	struct io_buffer *iobuf = NULL;
-	unsigned int quota = UNDI_POLL_QUOTA;
+	unsigned int quota = UNDI_RX_QUOTA;
 	size_t len;
 	size_t reserve_len;
 	size_t frag_len;
 	}
 
 	/* Run through the ISR loop */
-	while ( quota-- ) {
+	while ( quota ) {
 		profile_start ( &undinet_isr_call_profiler );
 		if ( ( rc = pxeparent_call ( undinet_entry, PXENV_UNDI_ISR,
 					     &undi_isr,
 			if ( iob_len ( iobuf ) == len ) {
 				/* Whole packet received; deliver it */
 				netdev_rx ( netdev, iob_disown ( iobuf ) );
+				quota--;
 				/* Etherboot 5.4 fails to return all packets
 				 * under mild load; pretend it retriggered.
 				 */