ARM: shmobile: Enable MICREL_PHY in shmobile_defconfig

commit 1c9106cb783cd227 ("ARM: shmobile: lager-reference: DTS-only board
support"), dropped the MACH_LAGER Kconfig section, which did "select
MICREL_PHY if SH_ETH". Hence we now have to enable MICREL_PHY explicitly
in shmobile_defconfig.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>