drm/i915/bxt: WA for swapped HPD pins in A stepping
WA for BXT A0/A1, where DDIB's HPD pin is swapped to DDIA, so enabling
DDIA HPD pin in place of DDIB.
v2: For DP, irq_port is used to determine the encoder instead of
hpd_pin and removing the edp HPD logic because port A HPD is not
present(Imre)
v3: Rebased on top of Imre's patchset for enabling HPD on PORT A.
Added hpd_pin swapping for intel_dp_init_connector, setting encoder
for PORT_A as per the WA in irq_port (Imre)
v4: Dont enable interrupt for edp, also reframe the description (Siva)
v5: Don’t check for PORT_A in intel_ddi_init to update dig_port,
instead avoid setting hpd_pin itself (Imre)