arch, devices, vmm: Remove "acpi" feature gate

Compile this feature in by default as it's well supported on both
aarch64 and x86_64 and we only officially support using it (no non-acpi
binaries are available.)

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

vmm/src/acpi.rs

@@ -13,7 +13,6 @@ use acpi_tables::{aml::Aml, rsdp::Rsdp, sdt::Sdt};
 use arch::aarch64::DeviceInfoForFdt;
 #[cfg(target_arch = "aarch64")]
 use arch::DeviceType;
-#[cfg(any(target_arch = "aarch64", feature = "acpi"))]
 use arch::NumaNodes;
 
 use bitflags::bitflags;