gpio-button-hotplug: remove #ifdef CONFIG_HOTPLUG, it is gone in newer kernels (fixes #16413)

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40838 3c298f89-4303-0410-b956-a3cf2f4a3e73
button-hotplug: remove #ifdef CONFIG_HOTPLUG, it is gone in newer kernels

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@40839 3c298f89-4303-0410-b956-a3cf2f4a3e73