drm/panel: Add Samsung prefix to panel drivers

The likelihood of getting a large number of panel drivers from different
vendors is quite high. Add a prefix to the two existing Samsung panel
drivers to set a guideline for future patch submissions. Using vendor
prefixes consistently should allow a cleaner organization of the tree.

Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>