ARM: shmobile: ape6evm: Use shmobile_init_delay()

The r8a73a4 DTS includes CPU Frequency information so
adjust the APE6EVM board code to use shmobile_init_delay()
instead of relying on CPU Frequency information included
in r8a73a4_init_delay() that is specified in C.

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