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: I794c658531483266bfce6f9b28127a166ed01490
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/configurations/meson.build b/configurations/meson.build
index 5c6c605..caf5aab 100644
--- a/configurations/meson.build
+++ b/configurations/meson.build
@@ -8,7 +8,7 @@
 install_data('fru_master.json', install_dir: package_datadir)
 endif
 
-if get_option('oem-ibm').enabled()
+if get_option('oem-ibm').allowed()
     install_subdir('../oem/ibm/configurations/fru', install_dir: package_datadir)
     install_subdir('../oem/ibm/configurations/events', install_dir: package_datadir)
     install_subdir('../oem/ibm/configurations/bios', install_dir: package_datadir)