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: I2253ebff36b49c4b79b803175dd76668f8ac2ba8
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meson.build b/meson.build
index ff1b127..d2f59d8 100644
--- a/meson.build
+++ b/meson.build
@@ -36,7 +36,7 @@
 
 conf = configuration_data()
 
-conf.set('CONFIG_PHAL_API', get_option('phal').enabled())
+conf.set('CONFIG_PHAL_API', get_option('phal').allowed())
 
 configure_file(input: 'config.h.in', output: 'config.h', configuration: conf)
 
@@ -66,7 +66,7 @@
 
 fmt_dep = dependency('fmt')
 
-if get_option('phal').enabled()
+if get_option('phal').allowed()
   libphal_dep = cmplr.find_library('phal')
 endif