pinctrl: sirf: enable GPIO pullup/down configuration from dts

commit 7bec207427c2efb794 remove sirfsoc_gpio_set_pull function,
this patches takes the feature back by adding sirf,pullups and
sirf,pulldowns prop in dts, and the driver will set the GPIO
pull according to the dts.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-sirf.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-sirf.txt
index a2896df..c596a6a 100644
--- a/Documentation/devicetree/bindings/pinctrl/pinctrl-sirf.txt
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-sirf.txt
@@ -6,6 +6,9 @@
 - interrupts    : Interrupts used by every GPIO group
 - gpio-controller : Indicates this device is a GPIO controller
 - interrupt-controller  : Marks the device node as an interrupt controller
+Optional properties:
+- sirf,pullups : if n-th bit of m-th bank is set, set a pullup on GPIO-n of bank m
+- sirf,pulldowns : if n-th bit of m-th bank is set, set a pulldown on GPIO-n of bank m
 
 Please refer to pinctrl-bindings.txt in this directory for details of the common
 pinctrl bindings used by client devices.