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/meson.options b/meson.options
index 7f39b00..26a7544 100644
--- a/meson.options
+++ b/meson.options
@@ -2,3 +2,4 @@
 option('tests', type: 'feature', description: 'Build tests')
 option('oem-ibm', type: 'feature', description: 'Enable IBM OEM PLDM')
 option('abi-compliance-check', type: 'feature', description: 'Detect public ABI/API changes')
+option('oem-meta', type: 'feature', description: 'Enable Meta OEM PLDM')
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