sh: ap_sh4a_4a: Fix wrong register initialization value

The value of ET0_ERXD6 and GPSR1_INIT was wrong.
This fixes them.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>