include/linux/mm.h: fix typo in VM_MPX definition

include/linux/mm.h: fix typo in VM_MPX definition

There's a typo in recent change of VM_MPX definition.  We want it to be
VM_HIGH_ARCH_4, not VM_HIGH_ARCH_BIT_4.

This bug does cause visible regressions.  In arch_vma_name the vmflags
are tested against VM_MPX.  With the incorrect value of VM_MPX, a number
of vmas (such as the stack) test positive and end up being marked as
"[mpx]" in /proc/N/maps instead of their correct names.

This confuses tools like rr which expect to be able to find familiar
vmas.

Fixes: df3735c5b40f ("x86,mpx: make mpx depend on x86-64 to free up VMA flag")
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Kirill A. Shutemov <[email protected]>
Reviewed-by: Rik van Riel <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Kyle Huey <[email protected]>
Cc: <[email protected]>	[4.14+]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>