pinctrl/nomadik: use simple or linear IRQ domain

This alters the Nomadik pinctrl driver to:

- Call irqdomain_add_linear() for the DT case so we get
  all independent from IRQ numbers in this case.
- Call irqdomain_add_simple() for the legacy case, which
  allocates the IRQ descriptors for the Nomadik pin controller
  dynamically.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>