Fix event table for Cortex A9.

Removed events 0x8 (INSTR_EXECUTED), 0xE (PC_PROC_RETURN) and
0x13-0x1d not supported on Cortex A9.
Add events 0x68 and 0x6E which replaced 0x8 and 0xE.

Submitted by: Michal Mazur <mkm@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield, Netgate
Differential revision: https://reviews.freebsd.org/D10911