dfu: fix Kconfig dependencies

dfu: fix Kconfig dependencies

Fix link errors caused by missing Kconfig dependencies:

1. DFU_OVER_USB compiles common/dfu.c which calls g_dnl_clear_detach()
which is implemented in drivers/usb/gadget/g_dnl.c which needs
USB_GADGET_DOWNLOAD. Test case:

 $ printf "CONFIG_USB_GADGET_DOWNLOAD=n\nCONFIG_USB_FUNCTION_FASTBOOT=n" \
       >>configs/am62px_evm_a53_defconfig
 $ make am62px_evm_a53_defconfig
 $ make CROSS_COMPILE=aarch64-linux-gnu-
 [...]
 common/dfu.c:34:(.text.run_usb_dnl_gadget+0x68): undefined reference to `g_dnl_clear_detach
 [...]

2. With the above fixed, the same build causes:

 common/spl/spl_dfu.c:29:(.text.spl_dfu_cmd+0xb0): undefined reference to `run_usb_dnl_gadget'

This is because SPL_DFU compiles common/spl/spl_dfu.c which calls
run_usb_dnl_gadget() which is implemented in common/dfu.c which needs
DFU_OVER_USB.

Therefore add these dependencies to Kconfig.

Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Link: https://lore.kernel.org/r/20240910102751.3182982-1-jerome.forissier@linaro.org
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>