build: use allowed over enabled

Meson feature options are typically in a tri-state of enabled, disabled,
or auto.  The enabled and disabled functions on an option (from
`get_option`) no longer return true for auto features.  Instead, the
expectation is to use `allowed()` which is true for both enabled and auto.

Switch all uses of `enabled` to `allowed`.

Change-Id: I309f22be2ecffc42fc987934ccaa2c0ba892d8e3
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meson.build b/meson.build
index 6ae1161..ed9a730 100644
--- a/meson.build
+++ b/meson.build
@@ -12,11 +12,11 @@
   ]
 )
 
-if(get_option('wait-for-os-standby').enabled())
+if(get_option('wait-for-os-standby').allowed())
   add_project_arguments('-DWAIT_FOR_OS_STANDBY', language : 'cpp')
 endif
 
-if(get_option('use-rdendpointcfg').enabled())
+if(get_option('use-rdendpointcfg').allowed())
   add_project_arguments('-DUSE_RDENDPOINTCFG', language : 'cpp')
 endif