meson: prefer allowed over enabled

Features are tri-states: enabled, disabled, unset.  There are
similarly 3 functions in meson: enabled(), disabled(), allowed().
Allowed should generally be preferred because it covers everything
except "enabled".  This also allows repository options to be
simplified so that "enabled" does not need to be specified in each
`meson.option`.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6e6f76c470a889b947ca076d35a99038993bb70d
diff --git a/meson.build b/meson.build
index 459421d..6a03c9a 100644
--- a/meson.build
+++ b/meson.build
@@ -68,11 +68,11 @@
 
 common_include = include_directories('.')
 
-common_build = build_tests.allowed() or get_option('bios-software-update').enabled() or get_option(
+common_build = build_tests.allowed() or get_option('bios-software-update').allowed() or get_option(
     'i2cvr-software-update',
-).enabled() or get_option(
+).allowed() or get_option(
     'eepromdevice-software-update',
-).enabled()
+).allowed()
 
 if common_build
     libpldm_dep = dependency('libpldm')
@@ -86,16 +86,16 @@
     subdir('common')
 endif
 
-if get_option('bios-software-update').enabled()
+if get_option('bios-software-update').allowed()
     subdir('bios')
 endif
 
-if get_option('i2cvr-software-update').enabled()
+if get_option('i2cvr-software-update').allowed()
     subdir('common/i2c/')
     subdir('i2c-vr')
 endif
 
-if get_option('eepromdevice-software-update').enabled()
+if get_option('eepromdevice-software-update').allowed()
     subdir('eeprom-device')
 endif