pcm052: allow specifying onboard DDR size in configs

PCM052 SoMs may be equipped with various sizes of DDR.
Keep default of 256MB; new PCM052-based targets will
specify their actual DDR size.

Linux command line is auto-adjusted to DDR size.

Signed-off-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>
diff --git a/board/phytec/pcm052/Kconfig b/board/phytec/pcm052/Kconfig
index d67a69a..88524a3 100644
--- a/board/phytec/pcm052/Kconfig
+++ b/board/phytec/pcm052/Kconfig
@@ -12,4 +12,8 @@
 config SYS_CONFIG_NAME
 	default "pcm052"
 
+config PCM052_DDR_SIZE
+	int
+	default 256
+
 endif