pinctrl: single: fix function name in documentation

Use the correct the function name in the documentation for
"pcs_parse_one_pinctrl_entry()".

"smux_parse_one_pinctrl_entry()" appears to be an artifact from the
development of a prior patch series ("simple pinmux driver") which
transformed into pinctrl-single.

Signed-off-by: Drew Fustini <drew@beagleboard.org>
Link: https://lore.kernel.org/r/20200612112758.GA3407886@x1
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-single.c

@@ -958,7 +958,7 @@ static int pcs_parse_pinconf(struct pcs_device *pcs, struct device_node *np,
 }
 
 /**
- * smux_parse_one_pinctrl_entry() - parses a device tree mux entry
+ * pcs_parse_one_pinctrl_entry() - parses a device tree mux entry
  * @pctldev: pin controller device
  * @pcs: pinctrl driver instance
  * @np: device node of the mux entry