util/cbfstool: Increase initrd offset to 64M

Newer Linux kernels fail to detect the initramfs using the old 16M
offset.  Increase the offset to the minimum working value, 64M.

Tested-on: qemu pc, 64-bit virtual CPU, linux 4.6 x86_64

Change-Id: I8678fc33eec23ca8f5e0d58723e04d434cd9d732
Signed-off-by: Timothy Pearson <tpearson@raptorengineering.com>
Reviewed-on: https://review.coreboot.org/15999
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
diff --git a/util/cbfstool/cbfs-payload-linux.c b/util/cbfstool/cbfs-payload-linux.c
index 79ee7ea..03a41cd 100644
--- a/util/cbfstool/cbfs-payload-linux.c
+++ b/util/cbfstool/cbfs-payload-linux.c
@@ -279,7 +279,7 @@
 		 * close to the kernel, so give it some room.
 		initrd_base = kernel_base + buffer_size(&bzp.kernel);
-		initrd_base = ALIGN(initrd_base, 16*1024*1024);
+		initrd_base = ALIGN(initrd_base, 64*1024*1024);
 		params.initrd_start = initrd_base;
 		params.initrd_size = buffer_size(&bzp.initrd);