pinctrl: s/have/has/ in GPIO driver interaction description

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/pinctrl.txt

@@ -286,7 +286,7 @@ see the section named "pin control requests from drivers" and
 "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 have its pinspace local to the pin
+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