There has been little to no attempt to document any of the demoted
structures here.  These are obviously not kerneldoc headers.

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

 drivers/pinctrl/bcm/pinctrl-bcm281xx.c:65: warning: cannot understand function prototype: 'enum bcm281xx_pin_type '
 drivers/pinctrl/bcm/pinctrl-bcm281xx.c:79: warning: cannot understand function prototype: 'struct bcm281xx_pin_function '
 drivers/pinctrl/bcm/pinctrl-bcm281xx.c:89: warning: cannot understand function prototype: 'struct bcm281xx_pinctrl_data '
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: YueHaibing <yuehaibing@huawei.com>
Link: https://lore.kernel.org/r/20200713144930.1034632-4-lee.jones@linaro.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>