PTR_ERR should access the value just tested by IS_ERR

The semantic patch that makes this change is available
in scripts/coccinelle/tests/odd_ptr_err.cocci.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>