sel4bench/morello: Add a new CPU with PMU events

[heshamelmatary]

Support new PMU event numbers for the Morello CPU. The first part of the numbers are from Neoverse N1 TRM [1] which the Morello CPU is based on, while the second part are Morello-specific numbers from the Morello TRM [2].

[1] https://developer.arm.com/documentation/100616/0400/ [2] https://developer.arm.com/documentation/den0133/latest