fix: fix build with clang-18

Some uses of inline assembly for accessing floating point registers did
not enable the FP extension and were failing with clang-18.

The check in the linker script for the `hftest_enable` variable fails
under clang-18. However, hftest still compiles and passes without the
check, so it was removed.

Fix new warnings from `clang-tidy`.

Apply `make format`.

Change-Id: I43996abb4c42de54be807dcdb76107b9752c62fb
Signed-off-by: Karl Meakin <karl.meakin@arm.com>
diff --git a/docs/getting_started/prerequisites.rst b/docs/getting_started/prerequisites.rst
index ba90ec6..d761e9f 100644
--- a/docs/getting_started/prerequisites.rst
+++ b/docs/getting_started/prerequisites.rst
@@ -17,13 +17,13 @@
 
 .. code:: shell
 
-   https://github.com/llvm/llvm-project/releases/download/llvmorg-17.0.6/clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04.tar.xz
+   https://github.com/llvm/llvm-project/releases/download/llvmorg-18.1.8/clang+llvm-18.1.8-x86_64-linux-gnu-ubuntu-18.04.tar.xz
 
 - For a AArch64 Ubuntu host,
 
 .. code:: shell
 
-   https://github.com/llvm/llvm-project/releases/download/llvmorg-17.0.6/clang+llvm-17.0.6-aarch64-linux-gnu.tar.xz
+   https://github.com/llvm/llvm-project/releases/download/llvmorg-18.1.8/clang+llvm-18.1.8-aarch64-linux-gnu.tar.xz
 
 .. note::
 
@@ -39,7 +39,7 @@
 
 .. code:: shell
 
-   PATH=<toolchain_dir>/clang+llvm-17.0.6-x86_64-linux-gnu-ubuntu-22.04/bin:$PATH
+   PATH=<toolchain_dir>/clang+llvm-18.1.8-x86_64-linux-gnu-ubuntu-18.04/bin:$PATH
 
 Dependencies
 ------------