ARM: shmobile: armadillo800eva: Conditionally select SMSC_PHY

The armadillo800eva board uses has an SH ethernet controller which uses an
SMSC phy. Select SMSC_PHY for koelsch if SH_ETH is enabled to make use of the
SMSC-specific phy driver rather than relying on the generic phy driver.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>