ARM: shmobile: Move r8a7791 reset code to pm-r8a7791.c

Move r8a7791 specific reset vector setup code from the
SMP glue code to PM code. This makes the code one step
closer to allow PM operations such as Suspend-to-RAM
in the case when SMP is disabled in the kernel config.

Signed-off-by: Magnus Damm <damm+renesas@opensource.se>
[horms+renesas@verge.net.au: updated for recent header file changes]
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>