selftests/powerpc/pmu: Add selftest for checking invalid bits in event code

Some of the bits in the event code is reserved for specific platforms.
Event code bits 52-59 are reserved in power9, whereas in power10, these
are used for programming Monitor Mode Control Register 3 (MMCR3). Bit 9
in event code is reserved in power9, whereas it is used for programming
"radix_scope_qual" bit 18 in Monitor Mode Control Register 1 (MMCR1).

Testcase to ensure that using reserved bits in event code should cause
event_open to fail.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-24-atrajeev@linux.vnet.ibm.com