ARM: OMAP2+: Fix legacy mode dss_reset

We must check for "dss_core" instead of "dss" to avoid also matching
also "dss_dispc". This only matters for the mixed case of data
configured in device tree but with legacy booting ti,hwmods property
still enabled.

Fixes: 8b30919a ("ARM: OMAP2+: Handle reset quirks for dynamically allocated modules")
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>