USB: f_accessory: Increase the IN endpoint buffer allocation

Some UDC may require allocation of some extra bytes for
TX buffer due to hardware requirement. Add necessary
changes for the same.

Change-Id: Ic4cdbce4ae422bbd2715ad95a7f35b1644c81bc1
Signed-off-by: Sujeet Kumar <ksujeet@codeaurora.org>
Signed-off-by: ChandanaKishori Chiluveru <cchilu@codeaurora.org>