ARM: shmobile: sh73a0: move global functions to sh73a0.h

There is no reason each CPU's own function has to exist in common.h.
sh73a0_xxx() go to sh73a0.h

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>