x86: remove old references to kmod-acpi-button

The kmod-acpi-button functionality is included in the kernel where needed
and the corresponding kmod package has been deleted long ago, therfor drop
the remaining references now.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

target/linux/x86/64/target.mk

 ARCH:=x86_64
 BOARDNAME:=x86_64
-DEFAULT_PACKAGES += kmod-acpi-button kmod-button-hotplug kmod-e1000e kmod-e1000 kmod-r8169
+DEFAULT_PACKAGES += kmod-button-hotplug kmod-e1000e kmod-e1000 kmod-r8169
 MAINTAINER:=Imre Kaloz <kaloz@openwrt.org>
 
 define Target/Description

target/linux/x86/kvm_guest/target.mk

 BOARDNAME:=KVM Guest
 FEATURES:=ext4 pci usb
-DEFAULT_PACKAGES += kmod-acpi-button kmod-button-hotplug kmod-virtio-balloon kmod-virtio-net kmod-virtio-random
+DEFAULT_PACKAGES += kmod-button-hotplug kmod-virtio-balloon kmod-virtio-net kmod-virtio-random
 CPU_TYPE := pentium4