ARM: ux500: Enable PL022 SSP Controller in Device Tree

This SSP Controller supports a number of serial communication methods
and as such cannot be registered using of_register_spi_devices.
Instead we register it simply as a primecell device.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>