board: starfive: function to read eMMC size

The EEPROM provides information about the size of the eMMC.
Provide a new function get_mmc_size_from_eeprom() to read it.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: E. Shattow <lucent@gmail.com>
diff --git a/board/starfive/visionfive2/Kconfig b/board/starfive/visionfive2/Kconfig
index 2186a93..d7e8a7a 100644
--- a/board/starfive/visionfive2/Kconfig
+++ b/board/starfive/visionfive2/Kconfig
@@ -50,4 +50,13 @@
 	imply PHY_LIB
 	imply PHY_MSCC
 
+config STARFIVE_NO_EMMC
+	bool "Report eMMC size as zero"
+	help
+	  The serial number string in the EEPROM is meant to report the
+	  size of onboard eMMC. Unfortunately some Milk-V Mars CM Lite
+	  modules without eMMC show a non-zero size here.
+
+	  Set to 'Y' if you have a Mars CM Lite module.
+
 endif