MAINTAINERS: stop nvme matching for nvmem files

The nvme patterns detect all include files starting with nvme, which
also picks up the nvmem subsystem header files. Fix this by using
a more specific pattern.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
[hch: switched to a purely inclusive pattern instead of excluding nvmem*]
Signed-off-by: Christoph Hellwig <hch@lst.de>