memstick: introduce correct definitions in the header

Thanks to some input from kind people at JMicron it is now possible to have
more correct definitions of protocol structures and bit field semantics.

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>