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: I3cac63961b6b7900433f259516702c6817c8956b
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/meson.build b/meson.build
index 245439e..782ac04 100644
--- a/meson.build
+++ b/meson.build
@@ -51,7 +51,7 @@
     'SYSFS_SECURE_BOOT_PATH', get_option('sysfs-secure-boot-path'))
 conf.set_quoted(
     'SYSFS_ABR_IMAGE_PATH', get_option('sysfs-abr-image-path'))
-if build_host_gpios.enabled()
+if build_host_gpios.allowed()
     conf.set_quoted(
         'HOST_GPIOS_BUSNAME', get_option('host-gpios-busname'))
     conf.set_quoted(
@@ -85,7 +85,7 @@
 
 configure_file(output: 'config.h', configuration: conf)
 
-if(get_option('warm-reboot').enabled())
+if(get_option('warm-reboot').allowed())
     add_project_arguments('-DENABLE_WARM_REBOOT',language:'cpp')
 endif
 
@@ -298,7 +298,7 @@
 subdir('service_files')
 subdir('target_files')
 
-if build_host_gpios.enabled()
+if build_host_gpios.allowed()
     subdir('host_condition_gpio')
 endif