drm/rockchip/dsi: fix handling mipi_dsi_pixel_format_to_bpp result

---
 drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
 
diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
index 7bfe243..f8f8f29 100644
--- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
+++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c
@@ -461,10 +461,11 @@ static int dw_mipi_dsi_phy_init(struct dw_mipi_dsi *dsi)
 
 static int dw_mipi_dsi_get_lane_bps(struct dw_mipi_dsi *dsi)
 {
-	unsigned int bpp, i, pre;
+	unsigned int i, pre;
 	unsigned long mpclk, pllref, tmp;
 	unsigned int m = 1, n = 1, target_mbps = 1000;
 	unsigned int max_mbps = dptdin_map[ARRAY_SIZE(dptdin_map) - 1].max_mbps;
+	int bpp;
 
 	bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
 	if (bpp < 0) {