OMAPDSS: Create new debug config options

The config option CONFIG_OMAP2_DSS_DEBUG_SUPPORT has been removed and replaced
with CONFIG_OMAP2_DSS_DEBUG and CONFIG_OMAP2_DSS_DEBUGFS. CONFIG_OMAP2_DSS_DEBUG
enables DEBUG flag and CONFIG_OMAP2_DSS_DEBUGFS enables creation of debugfs for
OMAPDSS. Both the config options are disabled by default and can be enabled
independently of one another as per convenience.

Signed-off-by: Chandrabhanu Mahapatra <cmahapatra@ti.com>
Reviewed-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>