hw/nvme: move nvme emulation out of hw/block

With the introduction of the nvme-subsystem device we are really
cluttering up the hw/block directory.

As suggested by Philippe previously, move the nvme emulation to hw/nvme.

Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 78561a2..e3c2866 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1956,7 +1956,7 @@
 M: Klaus Jensen <its@irrelevant.dk>
 L: qemu-block@nongnu.org
 S: Supported
-F: hw/block/nvme*
+F: hw/nvme/*
 F: include/block/nvme.h
 F: tests/qtest/nvme-test.c
 F: docs/system/nvme.rst