ARM: shmobile: Enable R-Car Gen2 CMA code in board files

Hook in the R-Car Gen2 CMA reservation code in the board
files for Lager and Koelsch. Both the DT-reference code
and the legacy code is modified.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>