Fix logic error in SkipCutBuffer.cpp

When allocate a new larger buffer, as it is a ring buffer, if
mWriteHead < mReadHead, it means available data isn't continuous,
so need to call memcpy twice to move previous data to new buffer.

Signed-off-by: xiahong.bao <xiahong.bao@nxp.com>
Change-Id: Idcdb61c3bb777cf13fd8805f22c862ccc200dbd4