ARM: shmobile: r8a7791: smp: remap whole apmu region

Documentation says the last register is at 0x184 (CAxCPUCMCR), so use
proper length. Current APMU code accesses CAxCPUnCR which is currently
outside of the remapped area.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>