usb: gadget: composite: Handle OS descriptor request properly

In case w_index or w_value of an OS descriptor does not match
for a device or an interface, value remains set to -EOPNOTSUPP.
This is assigned to an unsigned request length and becomes a
large integer value. When driver tries to allocate a buffer
of this large integer value DMA allocator complaints for out of
SW-IOMMU space. Hence check this variable for negative value and
return without queuing ep0 request.

CRs-Fixed: 1013316
Change-Id: I705d0d54fb17ca3042533f0106f91912215bd52a
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>