usb: android: Fix crash during audio unbind

As part of composition switch usb_remove_config
is called which takes care of calling func_unbind
of all functions present in that config. It also
calls android_unbind_config which results in calling
audio func_unbind again due to usb_remove_function
call. As android_remove_config takes care of removing
or unbinding functions as well, functions in android.c
don't need to call usb_remove_function which can cause
memory/list corruption.

Change-Id: Iced43efe4bbee44039f8994e5c8f2eb4484c0e54
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>