x86: cpa: rename global_flush_tlb() to cpa_flush_all()

The function name global_flush_tlb() suggests something different from
what the function really does. Rename it to cpa_flush_all(), which is an
understandable counterpart to cpa_flush_range().

no global visibility of the old API anymore.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>