defconfig: 8960: enable Kprobes

Make Kprobes built in to reduce user intervention to use tools
which use it.

When not in use, enabling this option does not produce any
statistically significant overhead.

Change-Id: Ifa9690ae01b3370e40aecae4fc7f96b4e8966e28
Signed-off-by: Neil Leeder <nleeder@codeaurora.org>