Nokia RX-51: Revert back onenand defitions

In commit commit 43ede0bca7 ("Kconfig: Migrate MTDIDS_DEFAULT /
MTDPARTS_DEFAULT") were removed definitions for onenand partitions.

Revert them back and enable needed options for onenand support.

Signed-off-by: Pali Rohár <pali@kernel.org>

include/configs/nokia_rx51.h

@@ -133,12 +133,8 @@
 #define PART6_OFFS			0x004c0000
 #define PART6_MASK			0x00000000
 
-#ifdef ONENAND_SUPPORT
-
 #define CONFIG_SYS_ONENAND_BASE		ONENAND_MAP
 
-#endif
-
 /* Watchdog support */
 #define CONFIG_HW_WATCHDOG
 
@@ -163,13 +159,7 @@ int rx51_kp_getc(struct stdio_dev *sdev);
 #endif
 
 /* Environment information */
-#ifdef CONFIG_MTDPARTS_DEFAULT
-#define MTDPARTS "mtdparts=" CONFIG_MTDPARTS_DEFAULT "\0"
-#else
-#define MTDPARTS
-#endif
 #define CONFIG_EXTRA_ENV_SETTINGS \
-	MTDPARTS \
 	"usbtty=cdc_acm\0" \
 	"stdin=vga\0" \
 	"stdout=vga\0" \