iwlwifi: add tm commands for indirect register access

Create new testmode commands to suppot indirect access
of peripheral register.
- IWL_TM_CMD_APP2DEV_INDIRECT_REG_READ32
- IWL_TM_CMD_APP2DEV_INDIRECT_REG_WRITE32

Meanwhile, add affix "DIRECT" into original register access
commands for better discrimination with new commands.
- IWL_TM_CMD_APP2DEV_DIRECT_REG_READ32
- IWL_TM_CMD_APP2DEV_DIRECT_REG_WRITE32
- IWL_TM_CMD_APP2DEV_DIRECT_REG_WRITE8

Signed-off-by: Kenny Hsu <kenny.hsu@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>