imx: mx6ull: update the REFTOP_VBGADJ setting

According to design team, we need to set REFTOP_VBGADJ
in PMU MISC0 according to the REFTOP_TRIM[2:0] fuse. the
actually table is as below:

  '000" - set REFTOP_VBGADJ[2:0] to 3'b000
  '001" - set REFTOP_VBGADJ[2:0] to 3'b001
  '010" - set REFTOP_VBGADJ[2:0] to 3'b010
  '011" - set REFTOP_VBGADJ[2:0] to 3'b011
  '100" - set REFTOP_VBGADJ[2:0] to 3'b100
  '101" - set REFTOP_VBGADJ[2:0] to 3'b101
  '110" - set REFTOP_VBGADJ[2:0] to 3'b110
  '111" - set REFTOP_VBGADJ[2:0] to 3'b111

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Bai Ping <ping.bai@nxp.com>