pinctrl: introduce PINCTRL_STATE_DEFAULT, define hogs as that state

This provides a single centralized name for the default state.

Update PIN_MAP_* macros to use this state name, instead of requiring the
user to pass a state name in.

With this change, hog entries in the mapping table are defined as those
with state name PINCTRL_STATE_DEFAULT, i.e. all entries have the same
name. This interacts badly with the nested iteration over mapping table
entries in pinctrl_hog_maps() and pinctrl_hog_map() which would now
attempt to claim each hog mapping table entry multiple times. Replacing
the custom hog code with a simple pinctrl_get()/pinctrl_enable().

Update documentation and mapping tables to use this.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

include/linux/pinctrl/pinctrl.h

@@ -19,6 +19,8 @@
 #include <linux/list.h>
 #include <linux/seq_file.h>
 
+#define PINCTRL_STATE_DEFAULT "default"
+
 struct pinctrl_dev;
 struct pinmux_ops;
 struct pinconf_ops;