Welp, yeah, that small /boot partition is a problem
The '/md0' says we are dealing with "raid" arrays, I see no provision for Logical Volume Management.
/dev/md0 92M 86M 1.1M 99% /boot
All I can say is when we get the 2 older kernels removed form the system
a) live with the sloppyation as is and pay real close attention when new kernels are installed to remove the older kernels ( keep 2 kernels, never can tell what might happen, a backup kernel is a good thing to have on hand !) ;
b) Yikes ! Back up all data, turn the system down, and RE-partition with a larger /boot partition.
But to address the immediate issue, get us some operating room by removing 2 kernels and see if that latest kernel will install.
Hold your breath and try :
May not be able too, no operating head room to work in, or broken dependencies.
sudo dpkg --purge linux-image-3.2.0-23-generic
sudo dpkg --purge linux-headers-3.2.0-23-generic
If there is a problem, well, we just do "something" else to get to the root of things.
where there is a will there is a way