simpleperf: inject: Fix condition for using branch_addr

When seeing an ISB instruction, b == true means The ISB
performed a Context synchronization event. However, the
code treats it as a branch taken.

Bug: none
Test: run simpleperf inject for vmlinux manually
Change-Id: I75609a79678ec07017b8c51b61a529463cfe235e
1 file changed