Miscellaneous arm64 changes for 5.12.

* for-next/misc:
  arm64: Make CPU_BIG_ENDIAN depend on ld.bfd or ld.lld 13.0.0+
  arm64: vmlinux.ld.S: add assertion for tramp_pg_dir offset
  arm64: vmlinux.ld.S: add assertion for reserved_pg_dir offset
  arm64/ptdump:display the Linear Mapping start marker
  arm64: ptrace: Fix missing return in hw breakpoint code
  KVM: arm64: Move __hyp_set_vectors out of .hyp.text
  arm64: Include linux/io.h in mm/mmap.c
  arm64: cacheflush: Remove stale comment
  arm64: mm: Remove unused header file
  arm64/sparsemem: reduce SECTION_SIZE_BITS
  arm64/mm: Add warning for outside range requests in vmemmap_populate()
  arm64: Drop workaround for broken 'S' constraint with GCC 4.9