tests: meson: Push build configuration down to leaf directories

I feel this keeps things a bit more self-contained.

Change-Id: I68de6e4b0269d64b620b6c339825113e31074b4c
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/tests/oem/ibm/meson.build b/tests/oem/ibm/meson.build
new file mode 100644
index 0000000..94c2011
--- /dev/null
+++ b/tests/oem/ibm/meson.build
@@ -0,0 +1,4 @@
+tests += [
+  'oem/ibm/libpldm_fileio_test',
+  'oem/ibm/libpldm_host_test',
+]