drm/i915/dsi: drop unused but set variable vbp

Prepare for re-enabling -Wunused-but-set-variable.

The vbp is not used for anything in the readout, as we get
e.g. crtc_vtotal from BXT_MIPI_TRANS_VTOTAL.
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/27efd245aa75226adcac01eff7b21781970f2736.1685119007.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/vlv_dsi.c

@@ -1039,7 +1039,7 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
 	unsigned int lane_count = intel_dsi->lane_count;
 	unsigned int bpp, fmt;
 	enum port port;
-	u16 hactive, hfp, hsync, hbp, vfp, vsync, vbp;
+	u16 hactive, hfp, hsync, hbp, vfp, vsync;
 	u16 hfp_sw, hsync_sw, hbp_sw;
 	u16 crtc_htotal_sw, crtc_hsync_start_sw, crtc_hsync_end_sw,
 				crtc_hblank_start_sw, crtc_hblank_end_sw;
@@ -1104,7 +1104,6 @@ static void bxt_dsi_get_pipe_config(struct intel_encoder *encoder,
 	/* vertical values are in terms of lines */
 	vfp = intel_de_read(dev_priv, MIPI_VFP_COUNT(port));
 	vsync = intel_de_read(dev_priv, MIPI_VSYNC_PADDING_COUNT(port));
-	vbp = intel_de_read(dev_priv, MIPI_VBP_COUNT(port));
 
 	adjusted_mode->crtc_htotal = hactive + hfp + hsync + hbp;
 	adjusted_mode->crtc_hsync_start = hfp + adjusted_mode->crtc_hdisplay;