openrisc: specify a memory region for u_boot_lists

Since there are two memory areas defined, vectors and ram,
the linker will error when neither of them are specified for a
section.

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>

board/openrisc/openrisc-generic/u-boot.lds

@@ -30,7 +30,7 @@ SECTIONS
 	 . = ALIGN(4);
 	 .u_boot_list : {
 		KEEP(*(SORT(.u_boot_list*)));
-	 }
+	 } > ram
 
 	.rodata : {
 		*(.rodata);