oem: meta: Add decode_oem_meta_file_io_req()

Support decode_oem_meta_file_io_req() cmd to decode the incoming post
code.

PLDM OEM Meta Write File IO cmd:
Example:
  Request:
    Byte 0: 0x3F (OEM cmd)
    Byte 1: 0x02 (FILE IO)
    Byte 2: 0x00 (File io type : POST CODE)
    Byte 3-6: 0x04 (Data length)
    Byte 7-10: 0x93 0xE0 0x00 0xEA (post code)

  Response:
    Byte 0: 0x00 (success)

Tested:
- Unit Tests passed.

Change-Id: I85437698642dd3cbe6084acf1feada842d206eac
Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>
diff --git a/src/meson.build b/src/meson.build
index 99e79a2..9f4487c 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -17,6 +17,10 @@
    subdir('oem/ibm')
 endif
 
+if get_option('oem-meta').allowed()
+   subdir('oem/meta')
+endif
+
 libpldm = library(
   'pldm',
    libpldm_sources,