meson.options: make dump-rotate-config kebab-case

Generally, feature options are kebab-case style and all of them
in phosphor-debug-collector are except this one.  Adjust it to
match the style.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ib2a51badc3d294b471e78810304bd2e690820868
diff --git a/meson.build b/meson.build
index bd246cb..c1d2801 100644
--- a/meson.build
+++ b/meson.build
@@ -160,7 +160,7 @@
 )
 conf_data.set(
     'BMC_DUMP_ROTATE_CONFIG',
-    get_option('dump_rotate_config').allowed(),
+    get_option('dump-rotate-config').allowed(),
     description: 'Turn on rotate config for bmc dump',
 )