perf/x86/amd/core: Always clear status for idx

In the Linux kernel, the following vulnerability has been resolved:

perf/x86/amd/core: Always clear status for idx

The variable 'status' (which contains the unhandled overflow bits) is
not being properly masked in some cases, displaying the following
warning:

WARNING: CPU: 156 PID: 475601 at arch/x86/events/amd/core.c:972 amd_pmu_v2_handle_irq+0x216/0x270

This seems to be happening because the loop is being continued before
the status bit being unset, in case x86_perf_event_set_period()
returns 0. This is also causing an inconsistency because the "handled"
counter is incremented, but the status bit is not cleaned.

Move the bit cleaning together above, together when the "handled"
counter is incremented.