imx: imximage: add new CHECK/CLR BIT command

* Extend imximage DCD version 2 to support DCD commands
  CMD_WRITE_CLR_BIT 4 [address] [mask bit] means:
    while ((*address & ~mask) != 0);
  CMD_CHECK_BITS_SET 4 [address] [mask bit] means:
    while ((*address & mask) != mask);
  CMD_CHECK_BITS_CLR 4 [address] [mask bit] means:
    *address = *address & ~mask;
* Add set_dcd_param_v2 helper function to set DCD
  command parameters

Signed-off-by: Adrian Alonso <aalonso@freescale.com>
Signed-off-by: Peng Fan <Peng.Fan@freescale.com>