pinctrl: atlas7: clear ugly branch statements for pull and drivestrength

To set/get atlas7 pull & drive strength, we use lots of if/else
to check pad type. But except mask value or immediate value, all
actions in these conditional branches are the same.
So we use predefined pull info table and drive strength table
to reduce these redundancy code.

Signed-off-by: Wei Chen <Wei.Chen@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>