MAINTAINERS: Fix F: in "QDev"

We neglected to update MAINTAINERS when we moved qdev headers from include/hw/ to include/hw/core/. Update it now. Fixes: 3775d19906 (include: move hw/qdev-clock.h to hw/core/, 2025-11-27) Fixes: d1000ecae2 (include: move hw/qdev-core.h to hw/core/, rename, 2025-11-27) Fixes: f7889f86bd (include: move hw/qdev-dma.h to hw/core/, 2025-11-27) Fixes: 78d45220b4 (include: move hw/qdev-properties.h to hw/core/, 2025-11-27) Fixes: e1e9a72500 (include: move hw/qdev-properties-system.h to hw/core/, 2025-11-27) Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Daniel P. Berrange <berrange@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Message-ID: <20260603064032.3733394-30-armbru@redhat.com>