x86/vector: Rename send_cleanup_vector() to vector_schedule_cleanup()

Rename send_cleanup_vector() to vector_schedule_cleanup() to prepare for
replacing the vector cleanup IPI with a timer callback.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Xin Li <xin3.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Steve Wahl <steve.wahl@hpe.com>
Link: https://lore.kernel.org/r/20230621171248.6805-2-xin3.li@intel.com