usb: sisusb_con: Use array_size() helper in memcpy()

Use array_size() helper instead of the open-coded version in memcpy().
These sorts of multiplication factors need to be wrapped in array_size().

This issue was found with the help of Coccinelle and, audited and fixed
manually.

Addresses-KSPP-ID: https://github.com/KSPP/linux/issues/83


Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20200615231827.GA21348@embeddedor


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