drm/panel: add S6E8AA0 driver

The patch adds MIPI-DSI based S6E8AA0 AMOLED LCD panel driver.
Driver uses mipi_dsi bus to communicate with panel and exposes drm_panel
interface.

v2
- added bus error handling,
- set maxmimum DSI packet size on init,
- removed unsupported brightness drm_panel callbacks,
- minor improvements

v3
- switched to gpiod framework,
- minor fixes in error handling

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>