soc: qcom: bgcom: fix dangling pointer on device shutdown

Make bgcom driver pointer as null on device shutdown.

Change-Id: I99b0334d8ccc59a9dc50ec148112a378b9664f3d
Signed-off-by: Ganesh Keethol <gkeethol@codeaurora.org>
diff --git a/drivers/soc/qcom/bgcom_spi.c b/drivers/soc/qcom/bgcom_spi.c
index a6a176a..ff07a32 100644
--- a/drivers/soc/qcom/bgcom_spi.c
+++ b/drivers/soc/qcom/bgcom_spi.c
@@ -1050,6 +1050,7 @@
 {
 	struct bg_spi_priv *bg_spi = spi_get_drvdata(spi);
 
+	bg_com_drv = NULL;
 	mutex_destroy(&bg_spi->xfer_mutex);
 	devm_kfree(&spi->dev, bg_spi);
 	spi_set_drvdata(spi, NULL);