spi: pl022: use pinctrl PM helpers

This utilize the new pinctrl core PM helpers to transition
the driver to "sleep" and "idle" states, cutting away some
boilerplate code.

Cc: Hebbar Gururaja <gururaja.hebbar@ti.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>