x86/mm: Remove unnecessary TLB flush for SME in-place encryption

A TLB flush is not required when doing in-place encryption or decryption
since the area's pagetable attributes are not being altered.  To avoid
confusion between what the routine is doing and what is documented in
the AMD APM, delete the local_flush_tlb() call.

Suggested-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20171101165426.1388.24866.stgit@tlendack-t1.amdoffice.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>