usb: dfu: Migrate CONFIG_SYS_DFU_DATA_BUF_SIZE and CONFIG_SYS_DFU_MAX_FILE_SIZE to Kconfig

Currently the config options CONFIG_SYS_DFU_DATA_BUF_SIZE and
CONFIG_SYS_DFU_MAX_FILE_SIZE are being set in include/configs/<board>.h
files and also in <board_name>_defconfig files without a Kconfig option. It
is easier for users to set these configs in defconfig files than in config
header files as they are a part of the source code.

Add Kconfig symbols, and update the defconfigs by using tools/moveconfig.py
script.

Suggested-by: Pratyush Yadav <p.yadav@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Acked-by: Oleksandr Suvorov <oleksandr.suvorov@toradex.com>
Acked-by: Matthias Brugger <mbrugger@suse.com>
Acked-by: Lukasz Majewski <lukma@denx.de>
diff --git a/configs/corvus_defconfig b/configs/corvus_defconfig
index 491f563..8206c4c 100644
--- a/configs/corvus_defconfig
+++ b/configs/corvus_defconfig
@@ -51,6 +51,7 @@
 CONFIG_CLK=y
 CONFIG_CLK_AT91=y
 CONFIG_DFU_NAND=y
+CONFIG_SYS_DFU_DATA_BUF_SIZE=0x100000
 CONFIG_AT91_GPIO=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y