clk: nomadik: fix missing __init on nomadik_src_init

nomadik_src_init references __initconst sections but lacks an __init
itself. Add __init to fix the section mismatch.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Olof Johansson <olof@lixom.net>