drm/ast: Fix incorrect register check for DRAM width

commit 2d02b8bd upstream.

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>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/gpu/drm/ast/ast_main.c

@@ -182,7 +182,7 @@ 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;