pinctrl: mvebu: complain about missing group after checking variant

Common MVEBU pinctrl driver core gets an array of controls to modify
a specific set of registers and an array of modes for each pingroup
from each of the different SoC families of MVEBU.

Some SoC families comprise different variants that differ in available
pingroups and also controls, but to ease driver development, we can
pass a variant mask to disable specific pingroups for some variants.
However, controls are limited to the true number of pinctrl groups
avaiable on a variant.

Now, when pinctrl core driver parses over above arrays, it tries to
match modes with available controls and complains about missing
controls for modes that are passed to the core but actually are not
avaiable on a variant with:

kirkwood-pinctrl f1010000.pin-controller: unknown pinctrl group 36

This warning is a false-positive and annoying, so move the warning
after we checked the variant mask for each mode setting. Also, if
there is no supported setting for this variant, do not complain at
all.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Reported-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>