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-regulators/meson.build b/phosphor-regulators/meson.build
index cd2c39c..a9a3dd5 100644
--- a/phosphor-regulators/meson.build
+++ b/phosphor-regulators/meson.build
@@ -4,6 +4,6 @@
 
 subdir('src')
 
-if get_option('tests').enabled()
+if get_option('tests').allowed()
     subdir('test')
 endif
diff --git a/phosphor-regulators/test/meson.build b/phosphor-regulators/test/meson.build
index b290cd0..74695be 100644
--- a/phosphor-regulators/test/meson.build
+++ b/phosphor-regulators/test/meson.build
@@ -52,7 +52,7 @@
 ]
 
 # Long-running tests that are excluded from CI
-if get_option('long-tests').enabled()
+if get_option('long-tests').allowed()
     # This test requires the Python module 'jsonschema'
     phosphor_regulators_tests_source_files += 'validate-regulators-config_tests.cpp'
 endif
@@ -69,7 +69,7 @@
                     sdbusplus,
                 ],
                 link_args: dynamic_linker,
-                build_rpath: get_option('oe-sdk').enabled() ? rpath : '',
+                build_rpath: get_option('oe-sdk').allowed() ? rpath : '',
                 link_with: [
                     phosphor_regulators_library,
                     libi2c_dev_mock