sh-pfc: Use devm_kzalloc()

Replace probe-time kmalloc()/kzalloc() calls with devm_kzalloc() and get
rid of the corresponding kfree() calls.

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