misc: move FLASH_MINOR into miscdevice.h and fix conflicts

FLASH_MINOR is used in both drivers/char/nwflash.c and
drivers/sbus/char/flash.c with conflict minor numbers.

Move all the definitions of FLASH_MINOR into miscdevice.h.
Rename FLASH_MINOR for drivers/char/nwflash.c to NWFLASH_MINOR
and FLASH_MINOR for drivers/sbus/char/flash.c to SBUS_FLASH_MINOR.

Link: https://lore.kernel.org/lkml/20200120221323.GJ15860@mit.edu/t/
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: "David S. Miller" <davem@davemloft.net>
Link: https://lore.kernel.org/r/20200311071654.335-3-zhenzhong.duan@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h
index 42360fc..66cc45e 100644
--- a/include/linux/miscdevice.h
+++ b/include/linux/miscdevice.h
@@ -30,12 +30,14 @@
 #define SUN_OPENPROM_MINOR	139
 #define DMAPI_MINOR		140	/* unused */
 #define NVRAM_MINOR		144
+#define SBUS_FLASH_MINOR	152
 #define SGI_MMTIMER		153
 #define PMU_MINOR		154
 #define STORE_QUEUE_MINOR	155	/* unused */
 #define LCD_MINOR		156
 #define AC_MINOR		157
 #define BUTTON_MINOR		158	/* Major 10, Minor 158, /dev/nwbutton */
+#define NWFLASH_MINOR		160	/* MAJOR is 10 - miscdevice */
 #define ENVCTRL_MINOR		162
 #define I2O_MINOR		166
 #define UCTRL_MINOR		174