Revert "usb: gadget: composite: always set ep->mult to a sensible value"

This reverts commit c53af76d which is
commit eaa496ffaaf19591fe471a36cef366146eeb9153 upstream as it was
incorrect.

Reported-by: Bin Liu <b-liu@ti.com>
Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>