schemas: use lower_snake_case for filenames

To be consistent with lower_snake_case source code filenames, use
lower_snake_case for schema file names as well.

Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
Change-Id: Id5ddeb4152a147229d522ddc0a1376875bfdfc78
diff --git a/meson.build b/meson.build
index e105f58..0e5d21d 100644
--- a/meson.build
+++ b/meson.build
@@ -165,12 +165,12 @@
     'global.json',
     'legacy.json',
     'openbmc-dbus.json',
-    'IBM.json',
-    'Intel.json',
-    'Pid.json',
-    'Pid.Zone.json',
-    'Stepwise.json',
-    'VirtualSensor.json',
+    'ibm.json',
+    'intel.json',
+    'pid.json',
+    'pid_zone.json',
+    'stepwise.json',
+    'virtual_sensor.json',
 ]
 
 foreach s : schemas