nvme: move to a new drivers/nvme/host directory

This patch moves the NVMe driver from drivers/block/ to its own new
drivers/nvme/host/ directory.  This is in preparation of splitting the
current monolithic driver up and add support for the upcoming NVMe
over Fabrics standard.  The drivers/nvme/host/ is chose to leave space
for a NVMe target implementation in addition to this host side driver.

Signed-off-by: Jay Sternberg <jay.e.sternberg@intel.com>
[hch: rebased, renamed core.c to pci.c, slight tweaks]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index 797236b..d104ec9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7448,7 +7448,7 @@
 L:	linux-nvme@lists.infradead.org
 T:	git git://git.infradead.org/users/willy/linux-nvme.git
 S:	Supported
-F:	drivers/block/nvme*
+F:	drivers/nvme/host/
 F:	include/linux/nvme.h
 
 NVMEM FRAMEWORK