video: fbdev: bt431: Correct cursor format control macro

The Bt431 cursor generator supports simultaneous generation of a 64 x 64
and a cross hair cursor in which the cursor format control bit (bit D4)
of the command register "specifies whether the contents of the cursor
RAM are to be logically exclusive-ORed (logical zero) or ORed (logical
one) with the cross hair cursor".  Rename the relevant macro accordingly.

References:

[1] "Bt431 Monolithic CMOS 64 x 64 Pixel Cursor Generator", Brooktree
    Corporation, Document Number: L431001, Rev. J
Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/bt431.h

@@ -63,7 +63,7 @@ static inline u8 bt431_get_value(u16 val)
 #define BT431_CMD_CURS_ENABLE	0x40
 #define BT431_CMD_XHAIR_ENABLE	0x20
 #define BT431_CMD_OR_CURSORS	0x10
-#define BT431_CMD_AND_CURSORS	0x00
+#define BT431_CMD_XOR_CURSORS	0x00
 #define BT431_CMD_1_1_MUX	0x00
 #define BT431_CMD_4_1_MUX	0x04
 #define BT431_CMD_5_1_MUX	0x08