spi: cadence-qspi: Make reset control optional

In the TI am65 device tree files there is no reset defined. Also
the Linux kernel driver uses devm_reset_control_get_optional_exclusive(..)
to get the reset.

Lets do the same as the kernel does and make thr reset optinal.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/drivers/spi/cadence_qspi.h b/drivers/spi/cadence_qspi.h
index 49b4011..19345ca 100644
--- a/drivers/spi/cadence_qspi.h
+++ b/drivers/spi/cadence_qspi.h
@@ -56,7 +56,7 @@
 	unsigned int	qspi_calibrated_cs;
 	unsigned int	previous_hz;
 
-	struct reset_ctl_bulk resets;
+	struct reset_ctl_bulk *resets;
 };
 
 /* Functions call declaration */