Non-conventional ferromagnetism and high bias magnetoresistance in <math altimg='"si18.svg"'> <mrow> <msub> <mrow> <mi mathvariant='"normal"'>TiO</mi> </mrow> <mrow> <mn>2</mn> <mo>-</mo> <mi>x</mi> </mrow> </msub> </mrow> </math> : A simple phenomenological approach