pinctrl: fix return value in bcm2835_pinctrl_probe()

In case of error, the function pinctrl_register() returns
NULL not ERR_PTR(). The PTR_ERR() in the return value
should be replaced with error no.

dpatch engine is used to auto generate this patch.
(https://github.com/weiyj/dpatch

)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>