MTP: Sanitize filename provided from MTP host

Fix potential security vulnerability via MTP path traversal

Bug: 130656917
Test: atest frameworks/av/media/mtp/tests
Test: Manual test: modified libmtp for path traversal attack
Test: Manual test: normal recursive folder copy
Change-Id: I467e1e6a76d09951050f7f45e5a63419e540c572