x86/asm/memcpy_mcsafe: Remove loop unrolling

x86/asm/memcpy_mcsafe: Remove loop unrolling

In preparation for teaching memcpy_mcsafe() to return 'bytes remaining'
rather than pass / fail, simplify the implementation to remove loop
unrolling. The unrolling complicates the fault handling for negligible
benefit given modern CPUs perform loop stream detection.

Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tony Luck <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: http://lkml.kernel.org/r/152539237092.31796.9115692316555638048.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Ingo Molnar <[email protected]>