drm/ast: Fix DRAM init on AST2200

Fix the test for the AST2200 in the DRAM initialization. The value
in ast->chip has to be compared against an enum constant instead of
a numerical value.

This bug got introduced when the driver was first imported into the
kernel.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Fixes: 312fec1 ("drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series (v2)")
Cc: Dave Airlie <airlied@redhat.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <stable@vger.kernel.org> # v3.5+
Reviewed-by: Sui Jingfeng <suijingfeng@loongson.cn>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Tested-by: Jocelyn Falempe <jfalempe@redhat.com> # AST2600
Link: https://patchwork.freedesktop.org/patch/msgid/20230621130032.3568-2-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_post.c

@@ -291,7 +291,7 @@ static void ast_init_dram_reg(struct drm_device *dev)
 				;
 			} while (ast_read32(ast, 0x10100) != 0xa8);
 		} else {/* AST2100/1100 */
-			if (ast->chip == AST2100 || ast->chip == 2200)
+			if (ast->chip == AST2100 || ast->chip == AST2200)
 				dram_reg_info = ast2100_dram_table_data;
 			else
 				dram_reg_info = ast1100_dram_table_data;