drm/radeon: unify bpc handling

We were already storing the bpc (bits per color) information
in radeon_crtc, so just use that everywhere rather than
calculating it everywhere we use it.  This also allows us
to change it in one place if we ever want to override it.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/atombios_crtc.c

@@ -559,7 +559,7 @@ static u32 atombios_adjust_pll(struct drm_crtc *crtc,
 	u32 adjusted_clock = mode->clock;
 	int encoder_mode = atombios_get_encoder_mode(encoder);
 	u32 dp_clock = mode->clock;
-	int bpc = radeon_get_monitor_bpc(connector);
+	int bpc = radeon_crtc->bpc;
 	bool is_duallink = radeon_dig_monitor_is_duallink(encoder, mode->clock);
 
 	/* reset the pll flags */