[ARM] 3614/1: ep93xx: use platform devices for physmap flash

Patch from Lennert Buytenhek

Now that the physmap platform device rewrite is in, make the ep93xx
boards use platform devices for physmap flash.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>