socfpga: Adding Freeze Controller driver

Adding Freeze Controller driver. All HPS IOs need to be
in freeze state during pin mux or IO buffer configuration.
It is to avoid any glitch which might happen
during the configuration from propagating to external devices.

Signed-off-by: Chin Liang See <clsee@altera.com>
Cc: Wolfgang Denk <wd@denx.de>
CC: Pavel Machek <pavel@denx.de>
Cc: Dinh Nguyen <dinguyen@altera.com>
Cc: Tom Rini <trini@ti.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>