The input arguments of av1_fht* and av1_iht* functions (and their
HBD versions) are slightly changed. Input arguments tx_type and
bd are carried by a struct fwd_txfm_param/inv_txfm_param. This
struct is meant to later on carry other prediction information,
such as intra top/left boundaries to the transform level, so
that the choice of transforms can be more adaptive to the
prediction mode and local video content.

Change-Id: Ia42544248a51845be64b72855b642ef1fe5910a9