net: qca_spi: Avoid reading signature three times in a row

There is no need to read the signature three times. So bail out
in case the second check failed.
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/qualcomm/qca_spi.c

@@ -506,6 +506,7 @@ qcaspi_qca7k_sync(struct qcaspi *qca, int event)
 		if (signature != QCASPI_GOOD_SIGNATURE) {
 			qca->sync = QCASPI_SYNC_UNKNOWN;
 			netdev_dbg(qca->net_dev, "sync: got CPU on, but signature was invalid, restart\n");
+			return;
 		} else {
 			/* ensure that the WRBUF is empty */
 			qcaspi_read_register(qca, SPI_REG_WRBUF_SPC_AVA,