drm/i915/lt_phy: Update the Tx Swing for DP 1.4

drm/i915/lt_phy: Update the Tx Swing for DP 1.4

Changes have been introduced in Bspec regarding the Tx Swing level,
Tx pre/post coefficients. Update the Tx Swing Level and the Tx
pre/post-cursor co-effecients to incorporate these changes

v2: Updated the commit message (Suraj)

BSpec: 74493
Signed-off-by: Arun R Murthy <arun.r.murthy@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patch.msgid.link/20260415043952.3189598-1-arun.r.murthy@intel.com