kernel: add exFAT fs driver

This was available since kernel 5.4.  The one provided in packages feed
will be considered deprecated and renamed to kmod-fs-exfat0.

Signed-off-by: DENG Qingfang <dengqf6@mail2.sysu.edu.cn>
Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
(use name kmod-fs-exfat.  use "@!(LINUX_4_4||LINUX_4_19)" for dependency)

package/kernel/linux/modules/fs.mk

@@ -163,6 +163,30 @@ endef
 $(eval $(call KernelPackage,fs-efivarfs))
 
 
+define KernelPackage/fs-exfat
+  SUBMENU:=$(FS_MENU)
+  TITLE:=exFAT filesystem support
+  KCONFIG:= \
+	CONFIG_EXFAT_FS \
+	CONFIG_EXFAT_DONT_MOUNT_VFAT=y \
+	CONFIG_EXFAT_DISCARD=y \
+	CONFIG_EXFAT_DELAYED_SYNC=n \
+	CONFIG_EXFAT_KERNEL_DEBUG=n \
+	CONFIG_EXFAT_DEBUG_MSG=n \
+	CONFIG_EXFAT_DEFAULT_CODEPAGE=437 \
+	CONFIG_EXFAT_DEFAULT_IOCHARSET="utf8"
+  FILES:=$(LINUX_DIR)/drivers/staging/exfat/exfat.ko
+  AUTOLOAD:=$(call AutoLoad,30,exfat,1)
+  DEPENDS:=@!(LINUX_4_4||LINUX_4_19) +kmod-nls-base
+endef
+
+define KernelPackage/fs-exfat/description
+ Kernel module for exFAT filesystem support
+endef
+
+$(eval $(call KernelPackage,fs-exfat))
+
+
 define KernelPackage/fs-exportfs
   SUBMENU:=$(FS_MENU)
   TITLE:=exportfs kernel server support