arm: pmu: Prepare for testing 64-bit overflows

PMUv3p5 adds a knob, PMCR_EL0.LP == 1, that allows overflowing at 64-bits
instead of 32. Prepare by doing these 3 things:

1. Add a "bool overflow_at_64bits" argument to all tests checking
   overflows.
2. Extend satisfy_prerequisites() to check if the machine supports
   "overflow_at_64bits".
3. Refactor the test invocations to use the new "run_test()" which adds a
   report prefix indicating whether the test uses 64 or 32-bit overflows.

A subsequent commit will actually add the 64-bit overflow tests.

Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Andrew Jones <andrew.jones@linux.dev>