mtd: fixup CFI on ixp4xx

drivers/mtd/maps/ixp4xx.c requires MTD_CFI_BE_BYTE_SWAP to be set
in order to compile.

drivers/mtd/maps/ixp4xx.c:57:4: error: #error CONFIG_MTD_CFI_BE_BYTE_SWAP required

This patch avoids the #error output by enforcing the policy in
Kconfig. Not sure if this is the right approach, but it helps doing
randconfig builds.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210927141045.1597593-1-arnd@kernel.org

drivers/mtd/chips/Kconfig

@@ -55,12 +55,14 @@ choice
 	  LITTLE_ENDIAN_BYTE, if the bytes are reversed.
 
 config MTD_CFI_NOSWAP
+	depends on !ARCH_IXP4XX || CPU_BIG_ENDIAN
 	bool "NO"
 
 config MTD_CFI_BE_BYTE_SWAP
 	bool "BIG_ENDIAN_BYTE"
 
 config MTD_CFI_LE_BYTE_SWAP
+	depends on !ARCH_IXP4XX
 	bool "LITTLE_ENDIAN_BYTE"
 
 endchoice

drivers/mtd/maps/Kconfig

@@ -302,7 +302,7 @@ config MTD_DC21285
 
 config MTD_IXP4XX
 	tristate "CFI Flash device mapped on Intel IXP4xx based systems"
-	depends on MTD_CFI && MTD_COMPLEX_MAPPINGS && ARCH_IXP4XX
+	depends on MTD_CFI && MTD_COMPLEX_MAPPINGS && ARCH_IXP4XX && MTD_CFI_ADV_OPTIONS
 	help
 	  This enables MTD access to flash devices on platforms based
 	  on Intel's IXP4xx family of network processors such as the