drm/radeon: remove the repeated declaration

Function 'r300_mc_wait_for_idle' and 'r600_mc_wait_for_idle'
are declared twice, remove the repeated declaration.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_asic.h

@@ -187,7 +187,6 @@ extern int rv370_pcie_gart_init(struct radeon_device *rdev);
 extern void rv370_pcie_gart_fini(struct radeon_device *rdev);
 extern int rv370_pcie_gart_enable(struct radeon_device *rdev);
 extern void rv370_pcie_gart_disable(struct radeon_device *rdev);
-extern int r300_mc_wait_for_idle(struct radeon_device *rdev);
 
 /*
  * r420,r423,rv410
@@ -404,7 +403,6 @@ void r600_hdmi_update_ACR(struct drm_encoder *encoder, uint32_t clock);
 void r600_hdmi_audio_workaround(struct drm_encoder *encoder);
 int r600_hdmi_buffer_status_changed(struct drm_encoder *encoder);
 void r600_hdmi_update_audio_settings(struct drm_encoder *encoder);
-int r600_mc_wait_for_idle(struct radeon_device *rdev);
 u32 r600_get_xclk(struct radeon_device *rdev);
 uint64_t r600_get_gpu_clock_counter(struct radeon_device *rdev);
 int rv6xx_get_temp(struct radeon_device *rdev);