usb: gadget: ncm: Remove transmit multi-frame support

Commit 6d3865f9 ("usb: gadget: NCM: Add transmit multi-frame.")
has added trasmit multi-frame support with NCM function. There are
different crashes seen on trying to assign IP Address with ncm network
interface. Hence revert this change until proper fix is found for these
crashes while enabling multi-frame support with NCM functionality.

Change-Id: I2ef3cf9a020697c4075b6d0b149d5a52c655f767
Signed-off-by: Mayank Rana <mrana@codeaurora.org>