drm/i915/dp: Program vswing, pre-emphasis, test-pattern

This patch process phy compliance request by programming requested
vswing, pre-emphasis and test pattern.

v1: Initial patch.
v2: Fixes added during testing with test-scope. (Khaled/Clint/Manasi)
- pipe used as argument during registers programming instead of port.
- TRANS_CONF must be disable/enable as well during ddi disable/enable.
- harcoded PLTPAT 80 bit custom pattern as the DPR-100 does not set it
in the sink’s DPCDs
- TRANS_DDI_FUNC_CTL DDI_Select (Bits 27:30) need to reset/set during
disable/enable.
v3: used macros instead of numbers and some cosmetic changes. [Manasi]

Cc: Clinton Taylor <Clinton.A.Taylor@intel.com>
Cc: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Khaled Almahallawy <khaled.almahallawy@intel.com>
Reviewed-by: Manasi Navare <manasi.d.navare@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200316103759.12867-8-animesh.manna@intel.com