ARM: shmobile: marzen: Add shmobile_init_late()

Extend board specific Marzen DT reference machine vector to include
shmobile_init_late() so Suspend-to-RAM and CPUIdle are setup as expected.

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