pinctrl: bcm: pinctrl-iproc-gpio: Rename incorrectly documented function param

pinctrl: bcm: pinctrl-iproc-gpio: Rename incorrectly documented function param

Fixes the following W=1 kernel build warning(s):

 drivers/pinctrl/bcm/pinctrl-iproc-gpio.c:141: warning: Function parameter or member 'chip' not described in 'iproc_set_bit'
 drivers/pinctrl/bcm/pinctrl-iproc-gpio.c:141: warning: Excess function parameter 'iproc_gpio' description in 'iproc_set_bit'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Link: https://lore.kernel.org/r/20200713144930.1034632-5-lee.jones@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>