x86/mm: Provide arch_prctl() interface for LAM

x86/mm: Provide arch_prctl() interface for LAM

Add a few of arch_prctl() handles:

 - ARCH_ENABLE_TAGGED_ADDR enabled LAM. The argument is required number
   of tag bits. It is rounded up to the nearest LAM mode that can
   provide it. For now only LAM_U57 is supported, with 6 tag bits.

 - ARCH_GET_UNTAG_MASK returns untag mask. It can indicates where tag
   bits located in the address.

 - ARCH_GET_MAX_TAG_BITS returns the maximum tag bits user can request.
   Zero if LAM is not supported.

Signed-off-by: Kirill A. Shutemov <[email protected]>
Signed-off-by: Dave Hansen <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Tested-by: Alexander Potapenko <[email protected]>
Link: https://lore.kernel.org/all/20230312112612.31869-9-kirill.shutemov%40linux.intel.com