drm/i915: drop buggy write to FDI_RX_CHICKEN register

Jani Nikula noticed that the parentheses are wrong and we & the bit
with the register address instead of the read-back value. He sent a
patch to correct that.

On second look, we write the same register in the previous line, and
the w/a seems to be to set FDI_RX_PHASE_SYNC_POINTER_OVR to enable the
logic, then keep always set FDI_RX_PHASE_SYNC_POINTER_OVR and toggle
FDI_RX_PHASE_SYNC_POINTER_EN before/after enabling the pc transcoder.

So the right things seems to be to simply kill the 2nd write.

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Dropped a bogus ~ from the commit message that somehow crept
in.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>