MLK-21891-2 fastboot: fix issue in enabling FAT_WRITE

Wrong config name is used in kconfig for selecting FAT_WRITE,
introduced by patch
(MLK-20594-2 enable fat write for all configuration with uuu)

Signed-off-by: Ye Li <ye.li@nxp.com>
diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
index 18afd7b..6ee9bb6 100644
--- a/drivers/fastboot/Kconfig
+++ b/drivers/fastboot/Kconfig
@@ -76,7 +76,7 @@
 	bool "Enable FASTBOOT i.MX UUU special command"
 	default y if ARCH_MX7 || ARCH_MX6 || ARCH_IMX8 || ARCH_IMX8M || ARCH_MX7ULP
 	select FSL_FASTBOOT
-	select CONFIG_FAT_WRITE
+	select FAT_WRITE
 	help
 	  The fastboot protocol includes "UCmd" command and "ACmd" command