f_fs: set maxburst to one before enabling endpoints

userspace is setting maxburst > 1 for IN endpoint as part of
descriptors passed to f_fs.c driver. Due to this, controller
driver allocating 3KB fifo instead of 1KB and results in fifo
allocations beyond available fifo size for last IN endpoint.
This causes functionality failure. Fix it as workaround by
setting maxburst to one so that only 1KB fifo is allocated for
adb IN endpoint.

Change-Id: I155da2dda408c02ca34a4e244094c4a66f288f74
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>