viresh.kumar@st.com email-id doesn't exist anymore as I have left the
company.  Replace ST's id with viresh.linux@gmail.com.

It also updates .mailmap file to fix address for 'git shortlog'
Signed-off-by: Viresh Kumar <viresh.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>