gpio: aggregator: fix "_sysfs" prefix check in gpio_aggregator_make_group()

gpio: aggregator: fix "_sysfs" prefix check in gpio_aggregator_make_group()

This code is intended to reject strings that start with "_sysfs" but the
strcmp() limit is wrong so checks the whole string instead of the prefix.

Fixes: 83c8e3df642f ("gpio: aggregator: expose aggregator created via legacy sysfs to configfs")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Koichiro Den <koichiro.den@canonical.com>
Link: https://lore.kernel.org/r/30210ed77b40b4b6629de659cb56b9ec7832c447.1744452787.git.dan.carpenter@linaro.org
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>