These decoders use a special non-MPEG2 IDCT.  Call it directly
instead of going through dsputil.  There is never any reason
to use a regular IDCT with these decoders or to use the EA IDCT
with other codecs.

This also fixes the bizarre situation of eamad and eatqi decoding
incorrectly if eatgq is disabled.

Signed-off-by: Mans Rullgard <mans@mansr.com>