Removed old lttng 2.1 bbappends

These bbappends no longer apply to lttng2.2.0.  The global_dirty_limit
patch is already included in lttng-modules 2.2.0, but the ARM syscalls
patch does not apply cleanly and must be redone if needed for the
3.5 or 3.8 kernels.
Merge pull request #3 from mbrown9764/clean-up-lttng-patches

Removed old lttng 2.1 bbappends