ARM: shmobile: lager: disable MMCIF Command Completion Signal, add CLK_CTRL2

MMCIF on r8a7790 doesn't support Command Completion Signal, but it does
implement a CE_CLK_CTRL2 register. Platform parameters have to be added to
account for these features on lager.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas@gmail.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>