drm/i915/gvt: remove gvt max port definition

Remove GVT-g private max port definition but use i915 one.

Fix error caused by:
drivers/gpu/drm/i915//gvt/handlers.c:871 dp_aux_ch_ctl_mmio_write() error: buffer overflow 'display->ports' 5 <= 5
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/gvt.h

@@ -132,11 +132,9 @@ struct intel_vgpu_opregion {
 
 #define vgpu_opregion(vgpu) (&(vgpu->opregion))
 
-#define INTEL_GVT_MAX_PORT 5
-
 struct intel_vgpu_display {
 	struct intel_vgpu_i2c_edid i2c_edid;
-	struct intel_vgpu_port ports[INTEL_GVT_MAX_PORT];
+	struct intel_vgpu_port ports[I915_MAX_PORTS];
 	struct intel_vgpu_sbi sbi;
 };