selftests/x86/lam: Add mmap and SYSCALL test cases for linear-address masking

Add mmap and SYSCALL test cases.

SYSCALL test cases:

 - LAM supports set metadata in high bits 62:57 (LAM_U57) of a user pointer, pass
   the pointer to SYSCALL, SYSCALL can dereference the pointer and return correct
   result.

 - Disable LAM, pass a pointer with metadata in high bits to SYSCALL,
   SYSCALL returns -1 (EFAULT).

MMAP test cases:

 - Enable LAM_U57, MMAP with low address (below bits 47), set metadata
   in high bits of the address, dereference the address should be
   allowed.

 - Enable LAM_U57, MMAP with high address (above bits 47), set metadata
   in high bits of the address, dereference the address should be
   allowed.

Signed-off-by: Weihong Zhang <weihong.zhang@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-14-kirill.shutemov%40linux.intel.com