meson: simplify sdbusplus dependency

There is a lot of cruft in the sdbusplus dependency that is no longer
needed:

    1. Use "dependency" with wrap file support rather than "subproject".

    2. Remove "include_type: system" since this is part of sdbusplus
       itself now.

    3. Leverage wrap file "provides" directives for dependency variable
       lookup.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7890258cc65381a2e5d1987c2d93c909210288cc
diff --git a/src/meson.build b/src/meson.build
index 3f98a6e..6fceae0 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -1,13 +1,7 @@
 phosphor_dbus_interfaces_dep = dependency('phosphor-dbus-interfaces')
 phosphor_logging_dep = dependency('phosphor-logging')
 
-sdbusplus_dep = dependency('sdbusplus', required: false, include_type: 'system')
-if not sdbusplus_dep.found()
-    sdbusplus_proj = subproject('sdbusplus', required: true)
-    sdbusplus = sdbusplus_proj.get_variable('sdbusplus_dep')
-    sdbusplus = sdbusplus.as_system('system')
-endif
-
+sdbusplus_dep = dependency('sdbusplus')
 stdplus_dep = dependency('stdplus')
 
 boost_dep = dependency('boost', version: '>=1.78.0', include_type: 'system')