RISC-V: Add MASK vec_duplicate pattern[PR110962]

This patch fix bug:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110962

SUBROUTINE a(b,c,d)
  LOGICAL,DIMENSION(INOUT)  :: b
  LOGICAL e
  REAL, DIMENSION(IN)     ::  c
  REAL, DIMENSION(INOUT)  ::  d
  REAL, DIMENSION(SIZE(c))   :: f
  WHERE (b.AND.e)
     WHERE (f>=0.)
        d = g
     ENDWHERE
  ENDWHERE
END SUBROUTINE a

   PR target/110962

gcc/ChangeLog:
	PR target/110962
	* config/riscv/autovec.md (vec_duplicate<mode>): New pattern.