sh-pfc: sh_pfc_probe() sizeof() fix

Fix sizeof() usage in sh-pfc/core.c to allocate space
for the full data structure instead of a pointer.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>