drm/i915/mtl: Skip doubling channel numbers for LPDDR4/LPDDDR5

MTL LPDDR5 reported 16b with 8 channels. Previous platforms
reported 32b with 4 channels and hence needed a multiplication
by a factor of 2. Skip increasing the channels for MTL.

v2: Use version check instead of platform check(MattR)

Bspec: 64631
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221117213015.584417-2-radhakrishna.sripada@intel.com

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

@@ -439,7 +439,8 @@ static int tgl_get_bw_info(struct drm_i915_private *dev_priv, const struct intel
 		return ret;
 	}
 
-	if (dram_info->type == INTEL_DRAM_LPDDR4 || dram_info->type == INTEL_DRAM_LPDDR5)
+	if (DISPLAY_VER(dev_priv) < 14 &&
+	    (dram_info->type == INTEL_DRAM_LPDDR4 || dram_info->type == INTEL_DRAM_LPDDR5))
 		num_channels *= 2;
 
 	qi.deinterleave = qi.deinterleave ? : DIV_ROUND_UP(num_channels, is_y_tile ? 4 : 2);