OMAPDSS: use omapdss_compat_init() in other drivers

omapdss_compat_init() and omapdss_compat_uninit() is called internally
by omapdss. This patch moves the calls to omapfb, omap_vout and omapdrm
drivers. omapdrm driver can later remove the call after non-compat
support has been implemented in omapdrm.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>