tifm: fix the MemoryStick host fifo handling code

Additional input received from JMicron on MemoryStick host interfaces showed
that some assumtions in fifo handling code were incorrect.  This patch also
fixes data corruption used to occure during PIO transfers.

Signed-off-by: Alex Dubov <oakad@yahoo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>