pinctrl: core: Set ret to 0 when group is skipped

Static analyzer tool found that the ret variable is not initialized but
code expects ret value >=0 when pinconf is skipped in the first pinmux
loop. The same expectation is for pinmux in a pinconf loop.
That's why initialize ret to 0 to avoid uninitialized ret value in first
loop or reusing ret value from first loop in second.

Addresses-Coverity: ("Uninitialized variables")
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/e5203bae68eb94b4b8b4e67e5e7b4d86bb989724.1615534291.git.michal.simek@xilinx.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>