Check the return code pointer value from debugfs_create_dir for error
or NULL.
Also added an additional check to prevent the creation of a 'suspend'
entry at the debugfs root in case a power domain directory cannot be
created.
Signed-off-by: NJean Pihet <j-pihet@ti.com>
Signed-off-by: NKevin Hilman <khilman@ti.com>