board: phytec: common: Define PHYTEC_API2_DATA_LEN

The EEPROM image length for API v2 is fixed to 32 bytes. No need
to use sizeof while this value won't change. This value is
also be required for API v3 to know where the API v3 header starts.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Tested-by: Wadim Egorov <w.egorov@phytec.de>
diff --git a/board/phytec/common/phytec_som_detection.c b/board/phytec/common/phytec_som_detection.c
index a089fe9..f0e35d8 100644
--- a/board/phytec/common/phytec_som_detection.c
+++ b/board/phytec/common/phytec_som_detection.c
@@ -78,13 +78,12 @@
 	int ret, i;
 	unsigned int crc;
 	u8 *ptr;
-	const unsigned int payload_size = sizeof(struct phytec_eeprom_payload);
 
 	if (!data)
 		data = &eeprom_data;
 
 	ret = phytec_eeprom_read((u8 *)data, bus_num, addr,
-				 payload_size, 0);
+				 PHYTEC_API2_DATA_LEN, 0);
 	if (ret)
 		goto err;
 
@@ -95,11 +94,11 @@
 	}
 
 	ptr = (u8 *)data;
-	for (i = 0; i < payload_size; ++i)
+	for (i = 0; i < PHYTEC_API2_DATA_LEN; ++i)
 		if (ptr[i] != 0x0)
 			break;
 
-	if (i == payload_size) {
+	if (i == PHYTEC_API2_DATA_LEN) {
 		pr_err("%s: EEPROM data is all zero. Erased?\n", __func__);
 		ret = -EINVAL;
 		goto err;
@@ -111,7 +110,7 @@
 		return 0;
 	}
 
-	crc = crc8(0, (const unsigned char *)&data->payload, payload_size);
+	crc = crc8(0, (const unsigned char *)&data->payload, PHYTEC_API2_DATA_LEN);
 	debug("%s: crc: %x\n", __func__, crc);
 
 	if (crc) {
diff --git a/board/phytec/common/phytec_som_detection.h b/board/phytec/common/phytec_som_detection.h
index 0ad5c14..1ccf36c 100644
--- a/board/phytec/common/phytec_som_detection.h
+++ b/board/phytec/common/phytec_som_detection.h
@@ -10,6 +10,8 @@
 #define PHYTEC_MAX_OPTIONS	17
 #define PHYTEC_EEPROM_INVAL	0xff
 
+#define PHYTEC_API2_DATA_LEN	32
+
 #define PHYTEC_GET_OPTION(option) \
 	(((option) > '9') ? (option) - 'A' + 10 : (option) - '0')