Bug fix when building pldm with oem-ibm diabled

Fixed issues that were seen when trying to build pldm with "oem-ibm"
disabled. Changed both the meson.build and pldmtool.cpp file to check
for the "oem-ibm" option.

Signed-off-by: Zahed Hossain <zahzahed@in.ibm.com>
Change-Id: If052cb6b8ff4dbb11d25ec2d0c0ea7828de3b0da
diff --git a/tool/meson.build b/tool/meson.build
index 12daf0d..48f4c26 100644
--- a/tool/meson.build
+++ b/tool/meson.build
@@ -7,9 +7,14 @@
   'pldm_bios_cmd.cpp',
   'pldm_fru_cmd.cpp',
   'pldmtool.cpp',
-  'oem/ibm/pldm_host_cmd.cpp'
 ]
 
+if get_option('oem-ibm').enabled()
+sources += [
+    'oem/ibm/pldm_host_cmd.cpp'
+  ]
+endif
+
 executable(
   'pldmtool',
   sources,