Compile the `mpu::RegisterBlock` struct on all targets
closes
use volatile_register::{RO, RW};
/// Register block for ARMv7-M
-#[cfg(any(armv6m, armv7m, target_arch = "x86_64"))] // x86-64 is for rustdoc
+#[cfg(not(armv8m))]
#[repr(C)]
pub struct RegisterBlock {
/// Type
