MAINTAINERS: Remove reference to non-existing file

GPIO HiSilicon driver doesn't provide any platform data header.

Fixes: a8f25236e6e3 ("MAINTAINERS: Add maintainer for HiSilicon GPIO driver")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20201214165524.43843-2-andriy.shevchenko@linux.intel.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>