NVMeMiFake: bug fix for unsupported log page

Add return to the error path, otherwise the callback will be triggered
twice.

Testd: unitest test passed
Signed-off-by: Hao Jiang <jianghao@google.com>
Change-Id: I817ce038139de8e63f7390f8c6a6434ecd6c3d5f

src/NVMeMiFake.hpp

diff --git a/src/NVMeMiFake.hpp b/src/NVMeMiFake.hpp
index 12e4875..e7bbe00 100644
--- a/src/NVMeMiFake.hpp
+++ b/src/NVMeMiFake.hpp
@@ -260,6 +260,7 @@
                 {
                     self->io.post(
                         [cb{cb}, ec = e.code()]() mutable { cb(ec, {}); });
+                    return;
                 }
                 self->io.post([cb{cb}, data{std::move(data)}]() mutable {
                     std::span<uint8_t> span{data.data(), data.size()};