mm/mglru: remove CONFIG_TRANSPARENT_HUGEPAGE

Improve code readability by removing CONFIG_TRANSPARENT_HUGEPAGE,
since the compiler should be able to automatically optimize out the
code that promotes THPs during page table walks.

No functional changes.

Link: https://lkml.kernel.org/r/20231227141205.2200125-6-kinseyho@google.com
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Co-developed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Tested-by: Donet Tom <donettom@linux.vnet.ibm.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>