blackfin: pinctrl-adi2: Enable PINCTRL framework for BF54x and BF60x.

- Remove unused macro MAX_RESOURCES
- Override blackfin legacy peripheral pinmux request and free APIs by
devm_pinctrl_get_select_default() to init the peripheral portmux setting.

v3-chagnes:
- Move pinctrl soc data out of blackfin arch folder.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Acked-by: Steven Miao <realmz6@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>