chromebook_samus: Increase pre-relocation memory

With bootstage now allocating pre-relocation memory the current amount
available is insufficient. Increase it a little.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/configs/chromebook_samus_defconfig b/configs/chromebook_samus_defconfig
index 8f2336c..e5483c5 100644
--- a/configs/chromebook_samus_defconfig
+++ b/configs/chromebook_samus_defconfig
@@ -1,6 +1,6 @@
 CONFIG_X86=y
 CONFIG_SYS_TEXT_BASE=0xFFE00000
-CONFIG_SYS_MALLOC_F_LEN=0x1800
+CONFIG_SYS_MALLOC_F_LEN=0x1a00
 CONFIG_DEBUG_UART_BOARD_INIT=y
 CONFIG_DEBUG_UART_BASE=0x3f8
 CONFIG_DEBUG_UART_CLOCK=1843200