staging: wfx: fix uninitialized variable bytes_done

staging: wfx: fix uninitialized variable bytes_done

The variable bytes_done is not initialized and hence the first
FIFO size check on bytes_done may be breaking prematurely from
the loop if bytes_done contains a large bogus uninitialized value.
Fix this by initializing bytes_done to zero.

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: a9408ad79ff3 ("staging: wfx: load the firmware faster")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200706132017.487627-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>