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: I1f8f77d3cd06d82c4d5390a910593f5e88c5581f
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/test/meson.build b/test/meson.build
index a0c7df8..440bec1 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -13,7 +13,7 @@
         gmock_dep = gtest_proj.dependency('gmock')
   else
         assert(
-            not get_option('tests').enabled(),
+            not get_option('tests').allowed(),
             'Googletest is required if tests are enabled'
         )
   endif
@@ -41,7 +41,7 @@
     ]
 endif
 
-if get_option('power10-support').enabled()
+if get_option('power10-support').allowed()
     test_sources += [
         '../powermode.cpp',
     ]