pinctrl: qcom: qdf2xxx: improve error checking and reporting

The driver doesn't report an error message if the ACPI tables are missing
the num-gpios property (which indicates how many GPIOs there are on this
SOC), and it didn't check to ensure that the mallocs didn't fail.

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Björn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>