video: fbdev: exynos: Remove old non-working MIPI driver

The old non-DRM Exynos MIPI driver does not support DeviceTree and
requires board files.  Our platforms do not provide such so the driver
is not usable since a long time ago.  All features provided by the
driver (and associated s6e8ax0 panel driver) are already supported by
newer DRM version so the old code can be removed.

Cc: Inki Dae <inki.dae@samsung.com>
Cc: Donghwa Lee <dh09.lee@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>