drm/msm/dsi: Use single function for reset

There is currently two function for performing reset: dsi_sw_reset and
dsi_sw_reset_restore. Only difference between those is that latter one
assumes that DSI controller is enabled. In contrary former one assumes
that controller is disabled and executed during power-on. However this
assumtion is not true mobile devices which have boot splash set up by
boot-loader.

This patch removes dsi_sw_reset_restore and makes dsi_sw_reset disable
DSI controller during reset sequence if it's enabled.

Signed-off-by: Vladimir Lypak <vladimir.lypak@gmail.com>
Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/489152/
Link: https://lore.kernel.org/r/20220610220259.220622-1-luca@z3ntu.xyz
[DB: fixed the typo in the commit message]
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>