block/swim: Rename macros to avoid inconsistent inverted logic

The Sony drive status bits use active-low logic. The swim_readbit()
function converts that to 'C' logic for readability. Hence, the
sense of the names of the status bit macros should not be inverted.

Mostly they are correct. However, the TWOMEG_DRIVE, MFM_MODE and
TWOMEG_MEDIA macros have inverted sense (like MkLinux). Fix this
inconsistency and make the following patches less confusing.

The same problem affects swim3.c so fix that too.

No functional change.

The FDHD drive status bits are documented in sonydriv.cpp from MAME
and in swimiii.h from MkLinux.

Cc: Laurent Vivier <lvivier@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: Jens Axboe <axboe@kernel.dk>
Cc: stable@vger.kernel.org # v4.14+
Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Acked-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>