drm/hisilicon: Fix DRM_INFO printed issue

This patch fixed the bellow no DRM_INFO is printed issue:

if (!delay_count)
	DRM_INFO("phylock and phystopstateclklane is not ready.\n");

There will some printed issues with above info, under certain
circumstances:

If ((BIT(0) | BIT(2)) & val) is never true, break will not happen and
delay_count will be max u32 value (?), and no DRM_INFO is printed.

Also if ((BIT(0) | BIT(2)) & val) is true at the last possible
loop round, break happens, but now delay_count is already zero
( because of earlier delay_count-- ) and DRM_INFO is erroneously
printed.

Thanks to Juha Leppänen, he reports to me this issue.

Signed-off-by: Xinliang Liu <xinliang.liu@linaro.org>
Reported-by: Juha Leppänen <juha_efku@dnainternet.net>

drivers/gpu/drm/hisilicon/kirin/dw_drm_dsi.c

@@ -430,12 +430,13 @@ static void dsi_set_mipi_phy(void __iomem *base,
 	 * wait for phy's clock ready
 	 */
 	delay_count = 100;
-	while (delay_count--) {
+	while (delay_count) {
 		val = readl(base +  PHY_STATUS);
 		if ((BIT(0) | BIT(2)) & val)
 			break;
 
 		udelay(1);
+		delay_count--;
 	}
 
 	if (!delay_count)