ARM: shmobile: defconfig: Enable SGTL5000 audio codec

The iWave RZ/G1M Q7 carrier board supports I2S audio codec "SGTL5000".

To increase hardware support enable the driver in the shmobile_defconfig
multiplatform configuration.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>