ARM: shmobile: r8a7779 SMP with SCU boot fn and args

Let r8a7779 make use of shmobile_boot_fn and shmobile_boot_arg
together with shmobile_boot_scu and the SCU base address.

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