ASoC: Update email-id of Rajeev Kumar

rajeev-dlh.kumar@st.com email-id doesn't exist anymore as I have left the
company.  Replace ST's id with Rajeev Kumar <rajeevkumar.linux@gmail.com>

Signed-off-by: Rajeev Kumar <rajeevkumar.linux@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>