KVM: vmx/pmu: Fix dummy check if lbr_desc->event is created

mainline inclusion
from mainline-v5.12-rc1
commit 67b45af9
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4NP0K
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=67b45af946ec3148b64e6a3a1ee2ea8f79c5bc07



-------------------

If lbr_desc->event is successfully created, the intel_pmu_create_
guest_lbr_event() will return 0, otherwise it will return -ENOENT,
and then jump to LBR msrs dummy handling.

Fixes: 1b5ac322 ("KVM: vmx/pmu: Pass-through LBR msrs when the guest LBR event is ACTIVE")
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20210223013958.1280444-1-like.xu@linux.intel.com>
[Add "< 0" and PTR_ERR to make the code clearer. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: WangJian <wangjian161@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>