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>
diff --git a/drivers/block/swim3.c b/drivers/block/swim3.c
index af51015..469541c 100644
--- a/drivers/block/swim3.c
+++ b/drivers/block/swim3.c
@@ -148,7 +148,7 @@ struct swim3 {
 #define MOTOR_ON	2
 #define RELAX		3	/* also eject in progress */
 #define READ_DATA_0	4
-#define TWOMEG_DRIVE	5
+#define ONEMEG_DRIVE	5
 #define SINGLE_SIDED	6	/* drive or diskette is 4MB type? */
 #define DRIVE_PRESENT	7
 #define DISK_IN		8
@@ -156,9 +156,9 @@ struct swim3 {
 #define TRACK_ZERO	10
 #define TACHO		11
 #define READ_DATA_1	12
-#define MFM_MODE	13
+#define GCR_MODE	13
 #define SEEK_COMPLETE	14
-#define ONEMEG_MEDIA	15
+#define TWOMEG_MEDIA	15
 
 /* Definitions of values used in writing and formatting */
 #define DATA_ESCAPE	0x99