efifb: support AMD Radeon HD 6490

This patch enables the framebuffer for the AMD Radeon 6490 found in the new MacBook Pro 8,2 generation.
The framebuffer's base is located at 0x90010000, the method for obtaining it was found in the same way mentioned in https://patchwork.kernel.org/patch/91704/

Signed-off-by: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: Jonathan Gonzalez <zeus@gnu.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c
index 70477c2..a9645b8 100644
--- a/drivers/video/efifb.c
+++ b/drivers/video/efifb.c
@@ -64,6 +64,7 @@
 	M_MBP_6_1,	/* MacBook Pro, 6,1th gen */
 	M_MBP_6_2,	/* MacBook Pro, 6,2th gen */
 	M_MBP_7_1,	/* MacBook Pro, 7,1th gen */
+	M_MBP_8_2,	/* MacBook Pro, 8,2nd gen */
 	M_UNKNOWN	/* placeholder */
 };
 
@@ -100,6 +101,7 @@
 	[M_MBP_6_1] = { "mbp61", 0x90030000, 2048 * 4, 1920, 1200 },
 	[M_MBP_6_2] = { "mbp62", 0x90030000, 2048 * 4, 1680, 1050 },
 	[M_MBP_7_1] = { "mbp71", 0xc0010000, 2048 * 4, 1280, 800 },
+	[M_MBP_8_2] = { "mbp82", 0x90010000, 1472 * 4, 1440, 900 },
 	[M_UNKNOWN] = { NULL, 0, 0, 0, 0 }
 };
 
@@ -151,6 +153,7 @@
 	EFIFB_DMI_SYSTEM_ID("Apple Inc.", "MacBookPro6,1", M_MBP_6_1),
 	EFIFB_DMI_SYSTEM_ID("Apple Inc.", "MacBookPro6,2", M_MBP_6_2),
 	EFIFB_DMI_SYSTEM_ID("Apple Inc.", "MacBookPro7,1", M_MBP_7_1),
+	EFIFB_DMI_SYSTEM_ID("Apple Inc.", "MacBookPro8,2", M_MBP_8_2),
 	{},
 };