tx493[89]ide: Remove big endian version of tx493[89]ide_tf_{load,read}

Now tx493[89]ide_tf_{load,read} do not contain word I/O operations.
They are endian-free now.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>,
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>