drm/i915/cnl: Fix CNL macros for Voltage Swing programming

drm/i915/cnl: Fix CNL macros for Voltage Swing programming

CNL macros for register groups CNL_PORT_TX_DW2_* / CNL_PORT_TX_DW5_* are
configured incorrectly wrt definition of _CNL_PORT_TX_DW_GRP.

v2: Jani suggested to keep the macros organized semantically i.e., by
function, secondarily by port/pipe/transcoder.->(dw, port)

Fixes: 4e53840fdfdd ("drm/i915/icl: Introduce new macros to get combophy registers")
Cc: Clint Taylor <clinton.a.taylor@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Aditya Swarup <aditya.swarup@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190110230844.9213-1-aditya.swarup@intel.com