OMAPDSS: HDMI: rename resource names

The HDMI driver tries to get the needed memory resources by name and by
ID. Resources by name are not currently defined, and will be used with
DT boot.

The resource names used in the driver are not quite perfect, and as they
are not used yet, we can change them. This patch removes the unneeded
"hdmi_" prefix from the names, and simplifies the names (e.g. hdmi_txphy
-> phy).

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