char: xillybus: Fix spelling mistake "overflew" -> "overflowed"

There is a spelling mistake in a dev_err message. Fix it.

Acked-by: Eli Billauer <eli.billauer@gmail.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210601102201.8489-1-colin.king@canonical.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>