meta-bletchley: bsp: set vmalloc to 512M

The vmalloc not automatic assigned correctly With 2048MB memory.
Manual append `vmalloc=512M` in bootargs to avoid boot issue of
vmap allocation failed.

Signed-off-by: Potin Lai <potin.lai@quantatw.com>
Change-Id: I11d3c8babb533ac94e81017da19feadeda45f1e2
diff --git a/meta-facebook/meta-bletchley/recipes-bsp/u-boot/u-boot-aspeed-sdk/bletchley.cfg b/meta-facebook/meta-bletchley/recipes-bsp/u-boot/u-boot-aspeed-sdk/bletchley.cfg
index cd6f2db..c958aa2 100644
--- a/meta-facebook/meta-bletchley/recipes-bsp/u-boot/u-boot-aspeed-sdk/bletchley.cfg
+++ b/meta-facebook/meta-bletchley/recipes-bsp/u-boot/u-boot-aspeed-sdk/bletchley.cfg
@@ -1,3 +1,3 @@
 CONFIG_USE_BOOTARGS=y
-CONFIG_BOOTARGS="console=ttyS4,57600n8 root=/dev/ram rw"
+CONFIG_BOOTARGS="console=ttyS4,57600n8 root=/dev/ram rw vmalloc=512M"
 CONFIG_BAUDRATE=57600