meta-bletchley: bsp: increase vmalloc to 768M

We notice the spi-aspeed-smc driver failed to

Tested on QEMU with 2GB memory:

- vmalloc=512M: spi-aspeed-smc shows ioremap failed

root@bletchley:~# dmesg | grep "Kernel command line:"
[    0.000000] Kernel command line: console=ttyS4,57600n8 root=/dev/ram rw vmalloc=512M
root@bletchley:~# dmesg | grep spi-aspeed-smc
[    2.410462] spi-aspeed-smc 1e620000.spi: CE0 read buswidth:2 [0x203b0641]
[    4.908989] spi-aspeed-smc 1e620000.spi: Calibration area too uniform, using low speed
[    4.909416] spi-aspeed-smc 1e620000.spi: CE1 read buswidth:2 [0x203b0041]
[    4.968292] spi-aspeed-smc 1e631000.spi: ioremap failed for resource [mem 0x50000000-0x5fffffff]
[    4.969035] spi-aspeed-smc 1e631000.spi: missing AHB mapping window
[    4.969301] spi-aspeed-smc: probe of 1e631000.spi failed with error -12

- vmalloc=768M: spi-aspeed-smc probe successfully

root@bletchley:~# dmesg | grep "Kernel command line:"
[    0.000000] Kernel command line: console=ttyS4,57600n8 root=/dev/ram rw vmalloc=768M
root@bletchley:~# dmesg | grep spi-aspeed-smc
[    2.672402] spi-aspeed-smc 1e620000.spi: CE0 read buswidth:2 [0x203b0641]
[    2.844554] spi-aspeed-smc 1e620000.spi: Calibration area too uniform, using low speed
[    2.845442] spi-aspeed-smc 1e620000.spi: CE1 read buswidth:2 [0x203b0041]

Signed-off-by: Potin Lai <potin.lai@quantatw.com>
Change-Id: I7ad7a2127a103db7cbefd6d89d42bd780294ceb0
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 c958aa2..1e2a374 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 vmalloc=512M"
+CONFIG_BOOTARGS="console=ttyS4,57600n8 root=/dev/ram rw vmalloc=768M"
 CONFIG_BAUDRATE=57600