drm/bridge/synopsys: dsi: Add 1.31 version support

Add support for the Synopsys DesignWare MIPI DSI version 1.31
Two registers need to be updated/added for supporting 1.31:
* PHY_TMR_CFG 0x9c (updated)
  1.30 [31:24] phy_hs2lp_time
       [23:16] phy_lp2hs_time
       [14: 0] max_rd_time

  1.31 [25:16] phy_hs2lp_time
       [ 9: 0] phy_lp2hs_time

* PHY_TMR_RD_CFG 0xf4 (new)
  1.31 [14: 0] max_rd_time

Signed-off-by: Philippe Cornu <philippe.cornu@st.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180206084251.303-1-philippe.cornu@st.com