Add likwid collector

collectors/likwid/groups/phi/TLB_L2.txt

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+SHORT L2 TLB misses
+
+EVENTSET
+PMC0 LONG_DATA_PAGE_WALK
+PMC1 DATA_READ_OR_WRITE
+
+METRICS
+Runtime (RDTSC) [s] time
+L2 TLB misses [misses/s] PMC0/time
+L2 TLB miss ratio PMC0/PMC1
+
+LONG
+Formulas:
+L2 TLB misses [misses/s] = LONG_DATA_PAGE_WALK/time
+L2 TLB miss ratio = LONG_DATA_PAGE_WALK/DATA_READ_OR_WRITE
+-
+This performance group measures the L2 TLB misses. A L2 TLB miss has a penelty
+of at least 100 cycles, hence it is important to avoid them. A high ratio can
+indicate trashing because when multiple pages are accessed in a loop iteration,
+the size and associativity is not sufficient to hold all pages. This would also
+result in a bad ratio for the L1 TLB.