board: phytec: Add SOM detection for AM6x

Add all functions to read each SOM option from the EEPROM
image and detect whether it's the correct product for this
image.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
diff --git a/board/phytec/common/Makefile b/board/phytec/common/Makefile
index 35c8174..3feb00f 100644
--- a/board/phytec/common/Makefile
+++ b/board/phytec/common/Makefile
@@ -8,4 +8,5 @@
 endif
 
 obj-y += phytec_som_detection.o
+obj-$(CONFIG_ARCH_K3) += am6_som_detection.o
 obj-$(CONFIG_ARCH_IMX8M) += imx8m_som_detection.o