Documentation: rename pinctl to pin-control

pinctl is not ideal as pinctrl (with an 'r') is much more common. Linus
state that pin-control.rst would be the best name for the documentation.

Link: https://lore.kernel.org/linux-gpio/20210126050817.GA187797@x1/#tSuggested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Drew Fustini <drew@beagleboard.org>
Link: https://lore.kernel.org/r/20210302053059.1049035-4-drew@beagleboard.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/driver-api/gpio/legacy.rst

@@ -461,7 +461,7 @@ pin controller?
 
 This is done by registering "ranges" of pins, which are essentially
 cross-reference tables. These are described in
-Documentation/driver-api/pinctl.rst
+Documentation/driver-api/pin-control.rst
 
 While the pin allocation is totally managed by the pinctrl subsystem,
 gpio (under gpiolib) is still maintained by gpio drivers. It may happen

Documentation/driver-api/index.rst

@@ -62,7 +62,7 @@ available subsections can be seen below.
    80211/index
    uio-howto
    firmware/index
-   pinctl
+   pin-control
    gpio/index
    md/index
    media/index

MAINTAINERS

@@ -14103,7 +14103,7 @@ L:	linux-gpio@vger.kernel.org
 S:	Maintained
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git
 F:	Documentation/devicetree/bindings/pinctrl/
-F:	Documentation/driver-api/pinctl.rst
+F:	Documentation/driver-api/pin-control.rst
 F:	drivers/pinctrl/
 F:	include/linux/pinctrl/