I’m using Linux 3.0.35 kernel on armhf platform. This supports only mysql 5.5. When will mysql 5.6 be available for debian armhf platform? Or is there any alternate method to install mysql 5.6 now itself?
It’s already available for armhf in experimental, see https://packages.debian.org/experimental/mysql-server-5.6
It won’t be part of Debian Jessie, I expect it will enter unstable once work starts on Stretch.
If you want to install it yourself, you can either install it from experimental, or try to build the Debian source (you can download it from the link above, look for the .dsc and associated files on the right). Both are likely to be complicated since you seem to be using an old distribution.