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: I37fcb391dcb215a86a60c26f7512f6ccb8312dc4
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/phosphor-power-supply/test/meson.build b/phosphor-power-supply/test/meson.build
index 1e5fe05..86143aa 100644
--- a/phosphor-power-supply/test/meson.build
+++ b/phosphor-power-supply/test/meson.build
@@ -21,7 +21,7 @@
                 link_with: [
                   libpower,
                   ],
-                build_rpath: get_option('oe-sdk').enabled() ? rpath : '',
+                build_rpath: get_option('oe-sdk').allowed() ? rpath : '',
                 objects: power_supply,
      )
 )