drivers: staging: android: Fix ashmem vm range comparison to stop roll-over

Every time ASHMEM_CACHE_INV_RANGE was sent to an IOCTL a roll-over was
occurring, causing the check to fail. This was comparing a start + size
range with a start + end range, and if the start + end was less than the
start + size the ioctl would fail. The end value was always equal to
start + size from all tests I ran, and since the roll-over occurred with
start + end, it was always less than start. Setting the check to compare
start + size > end fixes this.

Change-Id: I3e4356ab40d8c745fd91eb0cc6b1aaed73494140
Signed-off-by: Matthew Trusten <mtrusten@codeaurora.org>