[PATCH -next] drm/radeon: fix unsigned comparison with 0

[ChenTao]

Fixes warning because pipe is unsigned long and can never be negtative

vers/gpu/drm/radeon/radeon_kms.c:831:11: warning:
comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (pipe < 0 || pipe >= rdev->num_crtc) {
drivers/gpu/drm/radeon/radeon_kms.c:857:11: warning:
comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (pipe < 0 || pipe >= rdev->num_crtc) {

Reported-by: Hulk Robot <hulkci at huawei.com>
Signed-off-by: ChenTao <chentao107 at huawei.com>
---
 drivers/gpu/drm/radeon/radeon_kms.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 372962358a18..c5d1dc9618a4 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -828,7 +828,7 @@ int radeon_enable_vblank_kms(struct drm_crtc *crtc)
 	unsigned long irqflags;
 	int r;
 
-	if (pipe < 0 || pipe >= rdev->num_crtc) {
+	if (pipe >= rdev->num_crtc) {
 		DRM_ERROR("Invalid crtc %d\n", pipe);
 		return -EINVAL;
 	}
@@ -854,7 +854,7 @@ void radeon_disable_vblank_kms(struct drm_crtc *crtc)
 	struct radeon_device *rdev = dev->dev_private;
 	unsigned long irqflags;
 
-	if (pipe < 0 || pipe >= rdev->num_crtc) {
+	if (pipe >= rdev->num_crtc) {
 		DRM_ERROR("Invalid crtc %d\n", pipe);
 		return;
 	}
-- 
2.22.0