i2c: designware: add support of platform data to set I2C mode

Use the platform data to set the clk_freq when there is no DT configuration
available. The clk_freq in turn will determine the I2C speed mode.

In Quark, there is currently no other configuration mechanism other than
board files.

Signed-off-by: Raymond Tan <raymond.tan@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Hock Leong Kweh <hock.leong.kweh@intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/include/linux/platform_data/i2c-designware.h b/include/linux/platform_data/i2c-designware.h
new file mode 100644
index 0000000..7a61fb2
--- /dev/null
+++ b/include/linux/platform_data/i2c-designware.h
@@ -0,0 +1,21 @@
+/*
+ * Copyright(c) 2014 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef I2C_DESIGNWARE_H
+#define I2C_DESIGNWARE_H
+
+struct dw_i2c_platform_data {
+	unsigned int i2c_scl_freq;
+};
+
+#endif