sh: add kycr2_delay for sh_keysc

After KYCR2 is set, udelay might become necessary if there are only a
small number of keys attached. This patch introduces an optional delay
through the platform data to address this problem.

Signed-off-by: Kuninori Morimoto <morimoto.kuninori@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>