x86: x86-64: add arch_float_en-/dis-able() functions

This adds arch_float_enable() and arch_float_disable() to x86-64.
As x86-64 always has FP/SSE enabled, these operations are basically
no-ops. These are added just for the completeness of arch interface.

Fixes #38022

Signed-off-by: Daniel Leung <[email protected]>

Author: dcpleung

arch/x86/core/intel64/thread.c

@@ -61,3 +61,15 @@ void arch_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
 	thread->arch.flags = X86_THREAD_FLAG_ALL;
 	thread->switch_handle = thread;
 }
+
+int arch_float_disable(struct k_thread *thread)
+{
+	/* x86-64 always has FP/SSE enabled so cannot be disabled */
+	return -ENOTSUP;
+}
+
+int arch_float_enable(struct k_thread *thread, unsigned int options)
+{
+	/* x86-64 always has FP/SSE enabled so nothing to do here */
+	return 0;
+}