MAINTAINERS: remove section LIBNVDIMM BLK: MMIO-APERTURE DRIVER

MAINTAINERS: remove section LIBNVDIMM BLK: MMIO-APERTURE DRIVER

Commit f8669f1d6a86 ("nvdimm/blk: Delete the block-aperture window driver")
removes the file drivers/nvdimm/blk.c, but misses to adjust MAINTAINERS.

Hence, ./scripts/get_maintainer.pl --self-test=patterns complains about a
broken reference.

The section LIBNVDIMM BLK: MMIO-APERTURE DRIVER refers to the driver in
blk.c, and some more generic nvdimm code in region_devs.c.

As the driver is deleted, delete the section LIBNVDIMM BLK: MMIO-APERTURE
DRIVER in MAINTAINERS as well.

The remaining file region_devs.c is still covered by the section LIBNVDIMM:
NON-VOLATILE MEMORY DEVICE SUBSYSTEM, and all patches to region_devs.c will
still reach the same developers as before.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20220316052133.26212-1-lukas.bulwahn@gmail.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>