Lattice ECP3 FPGA: Check firmware pointer

This patch corrects a lack of testing.
If fw is NULL when calling firmware_load(), it results in a kernel oops.
Signed-off-by: Jean-Michel Hautbois <jean-michel.hautbois@vodalys.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/lattice-ecp3-config.c

@@ -79,6 +79,11 @@ static void firmware_load(const struct firmware *fw, void *context)
 	u32 jedec_id;
 	u32 status;
 
+	if (fw == NULL) {
+		dev_err(&spi->dev, "Cannot load firmware, aborting\n");
+		return;
+	}
+
 	if (fw->size == 0) {
 		dev_err(&spi->dev, "Error: Firmware size is 0!\n");
 		return;