sh: jump to p1 during boot on kfr2r09

Add a P1 jump to the the kfr2r09 romimage code. With this
patch applied the initial zImage assembly code will run
with instruction cache enabled.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>