perf vendor events intel: Add missing space in json descriptions

Add a missing space in the JSON description after the uncore unit

Before:

perf list
...
  unc_arb_coh_trk_requests.all
       [Unit: uncore_arbNumber of entries allocated. Account for Any type: e.g. Snoop, Core aperture, etc]
...

After:

  unc_arb_coh_trk_requests.all
       [Unit: uncore_arb Number of entries allocated. Account for Any type: e.g. Snoop, Core aperture, etc]

Cc: jolsa@kernel.org
Link: http://lkml.kernel.org/n/tip-p989c7x9kaiy2bnkmgpo6cvt@git.kernel.org
Signed-off-by: Andi Kleen <ak@linux.intel.com>