MTP: CPU usage high while under MTP mode.

poll timeout not setting well in MTP ffs handler.
This will cause MTP ffs handler not going into sleep mode.

Bug: 121171744
Test: MTP 500 Mbyte file copy throughput from / to Host (no drop)
Change-Id: I9b8a7257670b8e536bf2ea81118d297211254984
1 file changed