x86/acpi: Use %rip-relative addressing in wakeup_64.S

This is a "nice-to-have" change with minor code generation benefits:

 - Instruction with %rip-relative address operand is one byte shorter than
   its absolute address counterpart,

 - it is also compatible with position independent executable (-fpie) builds,

 - it is also consistent with what the compiler emits by default when
   a symbol is accessed.

No functional changes intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20231103104900.409470-1-ubizjak@gmail.com