drm/i915: Add missing MacBook Pro models with dual channel LVDS

Single channel LVDS maxes out at 112 MHz. The 15" pre-retina models
shipped with 1440x900 (106 MHz) by default or 1680x1050 (119 MHz)
as a BTO option, both versions used dual channel LVDS even though
the smaller one would have fit into a single channel.

Notes:
Bug report showing that the MacBookPro8,2 with 1440x900 uses dual
channel LVDS (this lead to it being hardcoded in intel_lvds.c by
Daniel Vetter with commit 618563e3945b9d0864154bab3c607865b557cecc):
https://bugzilla.kernel.org/show_bug.cgi?id=42842

If i915.lvds_channel_mode=2 is missing even though the machine needs
it, every other vertical line is white and consequently, only the left
half of the screen is visible (verified by myself on a MacBookPro9,1).

Forum posting concerning a MacBookPro6,2 with 1440x900, author is
using i915.lvds_channel_mode=2 on the kernel command line, proving
that the machine uses dual channels:
https://bbs.archlinux.org/viewtopic.php?id=185770

Chi Mei N154C6-L04 with 1440x900 is a replacement panel for all
MacBook Pro "A1286" models, and that model number encompasses the
MacBookPro6,2 / 8,2 / 9,1. Page 17 of the panel's datasheet shows it's
driven with dual channel LVDS:
http://www.ebay.com/itm/-/400690878560
http://www.everymac.com/ultimate-mac-lookup/?search_keywords=A1286
http://www.taopanel.com/chimei/datasheet/N154C6-L04.pdf

Those three 15" models, MacBookPro6,2 / 8,2 / 9,1, are the only ones
with i915 graphics and dual channel LVDS, so that list should be
complete. And the 8,2 is already in intel_lvds.c.

Possible motivation to use dual channel LVDS even on the 1440x900
models: Reduce the number of different parts, i.e. use identical logic
boards and display cabling on both versions and the only differing
component is the panel.

Signed-off-by: Lukas Wunner <[e-mail]>
Acked-by: Jani Nikula <[e-mail]>
Cc: [e-mail]
[Jani: included notes in the commit message for posterity]
Signed-off-by: Jani Nikula <[e-mail]>

drivers/gpu/drm/i915/intel_lvds.c

···
 static const struct dmi_system_id intel_dual_link_lvds[] = {
 	{
 		.callback = intel_dual_link_lvds_callback,
-		.ident = "Apple MacBook Pro (Core i5/i7 Series)",
+		.ident = "Apple MacBook Pro 15\" (2010)",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro6,2"),
+		},
+	},
+	{
+		.callback = intel_dual_link_lvds_callback,
+		.ident = "Apple MacBook Pro 15\" (2011)",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
 			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro8,2"),
+		},
+	},
+	{
+		.callback = intel_dual_link_lvds_callback,
+		.ident = "Apple MacBook Pro 15\" (2012)",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "MacBookPro9,1"),
 		},
 	},
 	{ }	/* terminating entry */