pinctrl.txt: Remove outdated information

		.confops = &foo_pconf_ops,

	};

Since some controllers have special logic for handling entire groups of pins

they can exploit the special whole-group pin control function. The

pin_config_group_set() callback is allowed to return the error code -EAGAIN,

for groups it does not want to handle, or if it just wants to do some

group-level handling and then fall through to iterate over all pins, in which

case each individual pin will be treated by separate pin_config_set() calls as

well.

Interaction with the GPIO subsystem

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