drm/i915/icl: Program HS_TX_TIMEOUT/LP_RX_TIMEOUT/TA_TIMEOUT registers

Program the timeout values (in escape clock) for HS TX, LP RX and TA
timeout.

HX TX: Ensure that host does not continuously transmit in the HS
state. If this timer expires, then host will gracefully end its HS
transmission and allow the link to enter into LP state.

LP RX: Monitor the length of LP receptions from Peripheral. If timeout
happens then host will drive the stop state onto all data lanes (only
Data Lane 0 should be receiving anything from the Peripheral). This
effectively takes back ownership of the bus transmit in the HS state.

TA timeout: Timeout valuefor monitoring Bus Turn-Around (BTA) sequence.
BTA sequence should complete within a bounded amount of time, with
peripheral acknowledging BTA by driving the stop state.

v2 by Jani:
 - Rebase
 - Use intel_dsi_bitrate() and intel_dsi_tlpx_ns(intel_dsi)
 - Squash HX TX, LP RX and TA timeout into one patch
 - Fix bspec mode set sequence reference
 - Add FIXME about two timeouts

Signed-off-by: Madhav Chauhan <madhav.chauhan@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/60e610ccffe5f8c09dee1c65828f28f25227efce.1540900289.git.jani.nikula@intel.com