Added sample for ISR register and unregister.

In this example, IRQ line 21 is considered because it is
shared between different devices.

Signed-off-by: Jeyaraman R <rjayavrp2@gmail.com>
Renamed ISR folder.

Signed-off-by: Jeyaraman Rangasamy <jeyaraman.rangasamy@lge.com>
Merge branch 'master' of https://github.com/jeyaramvrp/kernel-module-programming
Renamed Folder.

Signed-off-by: Jeyaraman R <rjayavrp@gmail.com>