socfpga/dwmmc: Adding DesignWare MMC driver support for SOCFPGA

To add the DesignWare MMC driver support for Altera SOCFPGA. It
required information such as clocks and bus width from platform
specific files (SOCFPGA handoff files)

Signed-off-by: Chin Liang See <clsee@altera.com>
Cc: Rajeshwari Shinde <rajeshwari.s@samsung.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>
Cc: Wolfgang Denk <wd@denx.de>
Acked-by: Pantelis Antoniou <panto@antoniou-consulting.com>