Update annotations in common/inc/sgx_tseal.h

suggested changes to aviod confusion:
typedef struct _aes_gcm_data_t
{
-uint32_t payload_size; /* 0: Size of the payload which includes both the encrypted data and the optional additional MAC text */
-uint8_t reserved[12]; /* 4: Reserved bits */
+uint32_t payload_size; /* 0: Size of the payload which includes the encrypted data: payload[] */
+uint8_t reserved[SGX_SEAL_IV_SIZE]; /* 4: Reserved bits used as iv */
uint8_t payload_tag[SGX_SEAL_TAG_SIZE]; /* 16: AES-GMAC of the plain text, payload, and the sizes */
-uint8_t payload[]; /* 32: The payload data which includes the encrypted data followed by the optional additional MAC text */
+uint8_t payload[]; /* 32: The payload data which includes the encrypted data followed by payload_tag */
} sgx_aes_gcm_data_t;

typedef struct _sealed_data_t
{
sgx_key_request_t key_request; /* 00: The key request used to obtain the sealing key */
-uint32_t plain_text_offset; /* 64: Offset within aes_data.playload to the start of the optional additional MAC text */
-uint8_t reserved[12]; /* 68: Reserved bits */
-sgx_aes_gcm_data_t aes_data; /* 80: Data structure holding the AES/GCM related data */
+uint32_t plain_text_offset; /* 512: Offset within aes_data.playload to the start of the optional additional MAC text */
+uint8_t reserved[12]; /* 516: Reserved bits */
+sgx_aes_gcm_data_t aes_data; /* 528: Data structure holding the AES/GCM related data */
} sgx_sealed_data_t;