drm/i915/display: Reset message bus after each read/write operation

drm/i915/display: Reset message bus after each read/write operation

Every know and then we receive the following error when running
for example IGT test kms_flip.

[drm] *ERROR* PHY G Read 0d80 failed after 3 retries.
[drm] *ERROR* PHY G Write 0d81 failed after 3 retries.

Since the error is sporadic in nature, the patch proposes
to reset the message bus after every successful or unsuccessful
read or write operation.

v2: Add FIXME's to indicate the experimental nature of
    this workaround (Rodrigo)
v3: Dropping the additional delay as moving reset to *_read_once()
    and *_write_once() functions seem unnecessary delay

Signed-off-by: Mika Kahola <mika.kahola@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231016125544.719963-1-mika.kahola@intel.com