perf vendor events intel: Add uncore_arb JSON support

The JSON lists call the box iMPH-U, while perf calls it arb.
Add conversion support to json to convert the unit properly.

Cc: jolsa@kernel.org
Link: http://lkml.kernel.org/n/tip-stq5ly95z2qioggp9bfaqe0h@git.kernel.orgSigned-off-by: NAndi Kleen <ak@linux.intel.com>

tools/perf/pmu-events/jevents.c

@@ -195,6 +195,7 @@ static struct map {
 	{ "CBO", "uncore_cbox" },
 	{ "QPI LL", "uncore_qpi" },
 	{ "SBO", "uncore_sbox" },
+	{ "iMPH-U", "uncore_arb" },
 	{}
 };