pinctrl: Reflow/wrap paragraph describing GPIO interaction

"drivers needing both pin control and GPIOs" below for details. But in some

situations a cross-subsystem mapping between pins and GPIOs is needed.

Since the pin controller subsystem has its pinspace local to the pin

controller we need a mapping so that the pin control subsystem can figure out

which pin controller handles control of a certain GPIO pin. Since a single

pin controller may be muxing several GPIO ranges (typically SoCs that have

one set of pins, but internally several GPIO silicon blocks, each modelled as

a struct gpio_chip) any number of GPIO ranges can be added to a pin controller

instance like this:

Since the pin controller subsystem has its pinspace local to the pin controller

we need a mapping so that the pin control subsystem can figure out which pin

controller handles control of a certain GPIO pin. Since a single pin controller

may be muxing several GPIO ranges (typically SoCs that have one set of pins,

but internally several GPIO silicon blocks, each modelled as a struct

gpio_chip) any number of GPIO ranges can be added to a pin controller instance

like this:

struct gpio_chip chip_a;

struct gpio_chip chip_b;