drm/i915: implement workaround for VTOTAL when using TRANSCODER_EDP
drm/i915: implement workaround for VTOTAL when using TRANSCODER_EDP

See the documentation for the DDI_FUNC_CTL register, EDP Input Select
bits: when the EDP input selection is B, the VTOTAL_B must be
programmed with the VTOTAL_EDP value, same thing for selection C.

V2: Use I915_READ as suggested by Daniel Vetter.

Signed-off-by: Paulo Zanoni <cc0e04a2103c45cd195651d976f79813d0f66bdf@intel.com>
Reviewed-by: Rodrigo Vivi <f714145d6ee82178e54021e0c168f56d17b53c9c@gmail.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs