ARM: poplar: Use Kconfig to enable CONFIG_FAT_WRITE

The symbol's been converted to Kconfig for a while, poplar is the only
one #defining it.

Signed-off-by: Tuomas Tynkkynen <tuomas@tuxera.com>

configs/poplar_defconfig

@@ -17,4 +17,5 @@ CONFIG_USB_EHCI_GENERIC=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_HOST_ETHER=y
 CONFIG_USB_ETHER_ASIX=y
+CONFIG_FAT_WRITE=y
 CONFIG_LIB_RAND=y

include/configs/poplar.h

@@ -66,7 +66,6 @@
 #define CONFIG_SYS_MMC_ENV_DEV		0
 #define CONFIG_ENV_OFFSET		(0x780 * 512)	/* env_mmc_blknum */
 #define CONFIG_ENV_SIZE			0x10000	/* env_mmc_nblks bytes */
-#define CONFIG_FAT_WRITE
 #define CONFIG_ENV_VARS_UBOOT_CONFIG
 
 /* Monitor Command Prompt */