perf/x86/amd: Reject branch stack for IBS events

The AMD IBS PMU doesn't handle branch stacks, so it should not accept
events with brstack.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231130062246.290-1-ravi.bangoria@amd.com