acpi_tables: Fix clippy warnings related to no_std and prelude imports

See - rust-lang/rust#121362 the recommendation
for how for no_std libraries has changed.

To avoid warnings around unncessary imports (due to the prelude when
compiling tests) make the tests also no_std and explicitly import the
require test dependencies.

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

src/aml.rs

@@ -1697,8 +1697,8 @@ impl<'a> Aml for PowerResource<'a> {
 
 #[cfg(test)]
 mod tests {
+    use alloc::borrow::ToOwned;
     use super::*;
-    use std::vec;
 
     #[test]
     fn test_device() {

src/bert.rs

@@ -62,6 +62,7 @@ aml_as_bytes!(BERT);
 
 #[cfg(test)]
 mod tests {
+    use alloc::vec::Vec;
     use super::*;
 
     #[test]

src/fadt.rs

@@ -245,6 +245,7 @@ impl FADTBuilder {
 
 #[cfg(test)]
 mod test {
+    use alloc::vec::Vec;
     use super::{FADTBuilder, Flags, PmProfile};
     use crate::Aml;
 

src/hmat.rs

@@ -357,7 +357,6 @@ impl Aml for MemorySideCache {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::Aml;
 
     fn check_checksum(hmat: &HMAT) {
         let mut bytes = Vec::new();

src/lib.rs

@@ -5,7 +5,7 @@
 //
 
 #![crate_type = "staticlib"]
-#![cfg_attr(not(test), no_std)]
+#![no_std]
 
 //! ACPI table generation.
 

src/madt.rs

@@ -649,7 +649,6 @@ aml_as_bytes!(PLIC);
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::Aml;
 
     fn check_checksum(madt: &MADT) {
         let mut bytes = Vec::new();

src/rhct.rs

@@ -335,7 +335,6 @@ impl Aml for MmuNode {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::Aml;
 
     #[test]
     fn test_rhct() {

src/rimt.rs

@@ -492,6 +492,7 @@ impl Aml for Platform {
 
 #[cfg(test)]
 mod tests {
+    use alloc::vec;
     use super::*;
 
     fn rimt() -> RIMT {

src/spcr.rs

@@ -167,6 +167,7 @@ impl SerialPortInfo {
 
 #[cfg(test)]
 mod tests {
+    use alloc::vec::Vec;
     use super::*;
 
     #[test]

src/tpm2.rs

@@ -304,6 +304,7 @@ impl Aml for Tpm2 {
 
 #[cfg(test)]
 mod tests {
+    use alloc::vec::Vec;
     use super::*;
     use crate::gas;
 

src/xsdt.rs

@@ -72,6 +72,7 @@ impl Aml for XSDT {
 
 #[cfg(test)]
 mod tests {
+    use alloc::vec::Vec;
     use super::XSDT;
     use crate::Aml;