platform: pldm_msgbuf for decode_set_numeric_effecter_value_req()

Also, make it at least possible to detect incorrect use of the API by
declaring `effecter_value` as a fixed-size array of 4.
Misuse is detected by -Wstringop-overflow with `gcc`, however failure
to uphold the requirement is ignored by `g++`, and both `clang` and
`clang++`.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: I5769db4d3c812d7feef994de836a8621fb4bf3cf
diff --git a/include/libpldm/platform.h b/include/libpldm/platform.h
index 9380bc9..dd4e9b8 100644
--- a/include/libpldm/platform.h
+++ b/include/libpldm/platform.h
@@ -1098,7 +1098,7 @@
 					  size_t payload_length,
 					  uint16_t *effecter_id,
 					  uint8_t *effecter_data_size,
-					  uint8_t *effecter_value);
+					  uint8_t effecter_value[4]);
 
 /** @brief Create a PLDM response message for SetNumericEffecterValue
  *