tools/testing/selftests/powerpc: Enable pmu selftests for power11

Add check for power11 pvr in the selftest utility
functions. Selftests uses pvr value to check for platform
support inorder to run the tests. pvr is also used to
send the extended mask value to capture sampling registers.

Update some of the utility functions to use hwcap2 inorder
to return platform specific bits from sampling registers.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250113075858.45137-1-atrajeev@linux.vnet.ibm.com