ARM: shmobile: Select CONFIG_REGULATOR in defconfig once again

eb451348
(ARM: shmobile: Enable kzm9g board in multiplatform defconfig)
dropped CONFIG_REGULATOR from shmobile_defconfig as it was
generated using a tree where CONFIG_REGULATOR is indirectly
selected by ARCH_SH73A0.

ARCH_SH73A0 is not queued up for v3.20 and thus, baring unforeseen
changes, CONFIG_REGULATOR will not be selected by shmobile_defconfig
in that release. This causes at least SDHI to stop working on
R-Car Gen2 SoCs.

Reported-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
[horms: minimal patch targeted as a fix]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>