OMAPDSS: rename display-sysfs 'name' entry

omapdss in compat mode creates some sysfs files into the device's sysfs
directory, including a 'name' file. This works fine for
platform_devices, but breaks with i2c or spi devices, as those already
have a 'name' file.

Fix this by renaming the omapdss's 'name' file to 'display_name'.

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