powerpc: Drop CONFIG_SYS_ALLOC_DPRAM

This is not defined anywhere in U-Boot. Drop this dead code.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/powerpc/include/asm/global_data.h b/arch/powerpc/include/asm/global_data.h
index 4090975..3943d0e 100644
--- a/arch/powerpc/include/asm/global_data.h
+++ b/arch/powerpc/include/asm/global_data.h
@@ -96,7 +96,7 @@
 	unsigned long arbiter_event_attributes;
 	unsigned long arbiter_event_address;
 #endif
-#if defined(CONFIG_SYS_ALLOC_DPRAM) || defined(CONFIG_CPM2)
+#if defined(CONFIG_CPM2)
 	unsigned int dp_alloc_base;
 	unsigned int dp_alloc_top;
 #endif