board: phytec: imx8m_som_detection: fix uninitialized pointer bug

Pointer in phytec_imx8m_detect was accessed without checking it first.
Fix this by moving the pointer check in front of any accesses.

Signed-off-by: Yannic Moog <y.moog@phytec.de>
diff --git a/board/phytec/common/imx8m_som_detection.c b/board/phytec/common/imx8m_som_detection.c
index 45f5767..a229eae 100644
--- a/board/phytec/common/imx8m_som_detection.c
+++ b/board/phytec/common/imx8m_som_detection.c
@@ -28,13 +28,13 @@
 	char *opt;
 	u8 som;
 
+	if (!data)
+		data = &eeprom_data;
+
 	/* We can not do the check for early API revisions */
 	if (data->api_rev < PHYTEC_API_REV2)
 		return -1;
 
-	if (!data)
-		data = &eeprom_data;
-
 	som = data->data.data_api2.som_no;
 	debug("%s: som id: %u\n", __func__, som);