drm/ast: Fix incorrect register check for DRAM width

[ Upstream commit 2d02b8bd ]

During DRAM initialization on certain ASpeed devices, an incorrect
bit (bit 10) was checked in the "SDRAM Bus Width Status" register
to determine DRAM width.

Query bit 6 instead in accordance with the Aspeed AST2050 datasheet v1.05.
Signed-off-by: Timothy Pearson <tpearson@raptorengineeringinc.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

drivers/gpu/drm/ast/ast_main.c

@@ -227,7 +227,7 @@ static int ast_get_dram_info(struct drm_device *dev)
 	} while (ast_read32(ast, 0x10000) != 0x01);
 	data = ast_read32(ast, 0x10004);
 
-	if (data & 0x400)
+	if (data & 0x40)
 		ast->dram_bus_width = 16;
 	else
 		ast->dram_bus_width = 32;