scripts/cocci: Rename memory-region-{init-ram -> housekeeping}

As we are going to add various semantic changes related to the memory
region API, rename this script to be more generic.
Add a 'usage' header, and an entry in MAINTAINERS to avoid checkpatch
warning.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

MAINTAINERS

@@ -2047,6 +2047,7 @@ F: include/exec/ramblock.h
 F: memory.c
 F: include/exec/memory-internal.h
 F: exec.c
+F: scripts/coccinelle/memory-region-housekeeping.cocci
 
 SPICE
 M: Gerd Hoffmann <kraxel@redhat.com>

scripts/coccinelle/memory-region-housekeeping.cocci

@@ -1,3 +1,16 @@
+/*
+  Usage:
+
+    spatch \
+        --macro-file scripts/cocci-macro-file.h \
+        --sp-file scripts/coccinelle/memory-region-housekeeping.cocci \
+        --keep-comments \
+        --in-place \
+        --dir .
+
+*/
+
+
 // Replace by-hand memory_region_init_ram_nomigrate/vmstate_register_ram
 // code sequences with use of the new memory_region_init_ram function.
 // Similarly for the _rom and _rom_device functions.