posix: return errFaultyDisk on I/O errors. (#1885)

When I/O error is occured more than allowed limit, posix returns
errFaultyDisk.

Fixes #1884

fs-v1-multipart.go

@@ -83,7 +83,7 @@ func (fs fsObjects) listMultipartUploads(bucket, prefix, keyMarker, uploadIDMark
 			// For any walk error return right away.
 			if walkResult.err != nil {
 				// File not found or Disk not found is a valid case.
-				if walkResult.err == errFileNotFound || walkResult.err == errDiskNotFound {
+				if walkResult.err == errFileNotFound || walkResult.err == errDiskNotFound || walkResult.err == errFaultyDisk {
 					eof = true
 					break
 				}