drivers/i2c/sx9310: Check for config not being NULL before using it

This change fixes the issue reported by Coverity CID 1393576 to ensure
that config is checked for NULL before it is actually used.

Change-Id: I5f0cd2bf2437fc640f4cf8d8203a971daf1f8d17
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/27207
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Enrico Granata <egranata@google.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/src/drivers/i2c/sx9310/sx9310.c b/src/drivers/i2c/sx9310/sx9310.c
index 7da87c4..5f63734 100644
--- a/src/drivers/i2c/sx9310/sx9310.c
+++ b/src/drivers/i2c/sx9310/sx9310.c
@@ -36,7 +36,7 @@
 	struct acpi_i2c i2c = {
 		.address = dev->path.i2c.device,
 		.mode_10bit = dev->path.i2c.mode_10bit,
-		.speed = config->speed ? : I2C_SPEED_FAST,
+		.speed = I2C_SPEED_FAST,
 		.resource = scope,
 	};
 	struct acpi_dp *dsd;
@@ -44,6 +44,9 @@
 	if (!dev->enabled || !scope || !config)
 		return;
 
+	if (config->speed)
+		i2c.speed = config->speed;
+
 	/* Device */
 	acpigen_write_scope(scope);
 	acpigen_write_device(acpi_device_name(dev));