Merge remote-tracking branch 'palmer/riscv-vdso-cleanup' into for-next

This contains a VDSO cleanup, along with a handful of VDSO fixes.  These
serve as a base for the new time namespace support, but are also on
fixes.

* palmer/riscv-vdso-cleanup:
  riscv/vdso: make arch_setup_additional_pages wait for mmap_sem for write killable
  riscv/vdso: Move vdso data page up front
  riscv/vdso: Refactor asm/vdso.h