[ARM] 5600/1: ep93xx: core.c remove cast when copying dev_addr

The MAC address for the ep93xx ethernet driver can be optionally
copied from registers in the controller when booting.  Due to
[ARM] 5573/1: ep93xx: ensure typesafe io, the cast for the source
address is no longer needed.

EP93XX_ETHERNET_BASE is typed as a (void __iomem __force *) so
memcpy_fromio() needs to be used instead of memcpy().

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>