meson: adjust nlohmann-json dependency

Simplify meson dependency logic and align wrap file name with other
repositories.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I516b4155786e4ae2d72c99e3e253c63db3752449
diff --git a/meson.build b/meson.build
index f73b214..67442b5 100644
--- a/meson.build
+++ b/meson.build
@@ -119,14 +119,7 @@
 sdbusplus_dep = dependency('sdbusplus')
 stdplus_dep = dependency('stdplus')
 
-if cpp.has_header_symbol(
-        'nlohmann/json.hpp',
-        'nlohmann::json::string_t',
-        required:false)
-    nlohmann_json_dep = declare_dependency()
-else
-    nlohmann_json_dep = dependency('nlohmann-json')
-endif
+nlohmann_json_dep = dependency('nlohmann_json', include_type: 'system')
 
 generated_src = []
 
diff --git a/subprojects/nlohmann-json.wrap b/subprojects/nlohmann-json.wrap
deleted file mode 100644
index a2884b1..0000000
--- a/subprojects/nlohmann-json.wrap
+++ /dev/null
@@ -1,6 +0,0 @@
-[wrap-git]
-url = https://github.com/nlohmann/json
-revision = HEAD
-
-[provide]
-nlohmann-json = nlohmann_json_dep
diff --git a/subprojects/nlohmann_json.wrap b/subprojects/nlohmann_json.wrap
new file mode 100644
index 0000000..3745380
--- /dev/null
+++ b/subprojects/nlohmann_json.wrap
@@ -0,0 +1,6 @@
+[wrap-git]
+revision = HEAD
+url = https://github.com/nlohmann/json.git
+
+[provide]
+nlohmann_json = nlohmann_json_dep