bios_table: pldm_bios_table_attr_entry_enum_decode_pv_num_check() values

Document the pre-conditions that lead to failures and their associated
error codes.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Ib283c73bbbf68415a12d5d2e9b24e39dbba44c0c
diff --git a/include/libpldm/bios_table.h b/include/libpldm/bios_table.h
index d21a386..128dac4 100644
--- a/include/libpldm/bios_table.h
+++ b/include/libpldm/bios_table.h
@@ -269,7 +269,8 @@
  * validity of the parameters
  *  @param[in] entry - Pointer to bios attribute table entry
  *  @param[out] pv_num - Pointer to total number of possible values
- *  @return pldm_completion_codes
+ *  @return PLDM_SUCCESS on success, PLDM_ERROR_INVALID_DATA if entry or pv_num are NULL, or
+ *          PLDM_ERROR_INVALID_DATA if entry is not a valid PLDM_BIOS_ENUMERATION
  */
 int pldm_bios_table_attr_entry_enum_decode_pv_num_check(
 	const struct pldm_bios_attr_table_entry *entry, uint8_t *pv_num);