ARM: 6124/1: ep93xx: SPI driver platform support code

This patch adds platform side support code for the EP93xx SPI
driver. This includes clock, resources and muxing. There is a new
function: ep93xx_register_spi() which can be used by board support
code to register new SPI devices for the board.

This patch depends on patch
  5998/1 ep93xx: added chip revision reading function

Cc: Ryan Mallon <ryan@bluewatersys.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Mika Westerberg <mika.westerberg@iki.fi>
Acked-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Martin Guy <martinwguy@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>