KVM: x86: Capture "struct x86_exception" in inject_emulated_exception()

KVM: x86: Capture "struct x86_exception" in inject_emulated_exception()

As all callers in inject_emulated_exception() use "struct x86_exception"
directly, capture it locally instead of using the context.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260515222638.1949982-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>