spi/orion: remove uneeded spi_info

This was formerly used to store the tclk value. This is now discovered
using the clk API, rather than pass it as platform data.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Jason Cooper <jason@lakedaemon.net>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@googlemail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>