fastboot: Migrate FASTBOOT_FLASH_NAND_TRIMFFS to Kconfig

Add FASTBOOT_FLASH_NAND_TRIMFFS to Kconfig; note there are no in-tree
users of it.

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/fastboot/Kconfig

@@ -86,6 +86,13 @@ config FASTBOOT_FLASH_MMC_DEV
 	  regarding the non-volatile storage device. Define this to
 	  the eMMC device that fastboot should use to store the image.
 
+config FASTBOOT_FLASH_NAND_TRIMFFS
+	bool "Skip empty pages when flashing NAND"
+	depends on FASTBOOT_FLASH_NAND
+	help
+	  When flashing NAND enable the DROP_FFS flag to drop trailing all-0xff
+	  pages.
+
 config FASTBOOT_GPT_NAME
 	string "Target name for updating GPT"
 	depends on FASTBOOT_FLASH_MMC && EFI_PARTITION

scripts/config_whitelist.txt

@@ -590,7 +590,6 @@ CONFIG_EXYNOS_SPL
 CONFIG_EXYNOS_TMU
 CONFIG_FACTORYSET
 CONFIG_FASTBOOT_FLASH_FILLBUF_SIZE
-CONFIG_FASTBOOT_FLASH_NAND_TRIMFFS
 CONFIG_FAST_FLASH_BIT
 CONFIG_FB_ADDR
 CONFIG_FB_BACKLIGHT