vexpress_ca9x4: Enable DM_SERIAL

This commit enables support for DM_SERIAL in the vexpress_ca9x4 boards.

When running the board with the DM_SERIAL driver, the board ran out of
memory in SPL when initialising the DM serial driver.

Thus this required an increase in the pre-allocated SRAM memory. I did
increase it to 0x800, and it now works graciously.

It could probably be set lower, but I do not see any reason not to use the
available SRAM at this point.

Also adds stdout-path to the 'chosen' node in the device tree.

Signed-off-by: Ole P. Orhagen <ole.orhagen@northern.tech>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/configs/vexpress_ca9x4_defconfig b/configs/vexpress_ca9x4_defconfig
index 2601e55..f8e93be 100644
--- a/configs/vexpress_ca9x4_defconfig
+++ b/configs/vexpress_ca9x4_defconfig
@@ -2,7 +2,7 @@
 CONFIG_SYS_L2CACHE_OFF=y
 CONFIG_TARGET_VEXPRESS_CA9X4=y
 CONFIG_TEXT_BASE=0x60800000
-CONFIG_SYS_MALLOC_F_LEN=0x400
+CONFIG_SYS_MALLOC_F_LEN=0x800
 CONFIG_NR_DRAM_BANKS=2
 CONFIG_HAS_CUSTOM_SYS_INIT_SP_ADDR=y
 CONFIG_CUSTOM_SYS_INIT_SP_ADDR=0x60000f10
@@ -41,6 +41,7 @@
 CONFIG_SYS_MMC_MAX_BLK_COUNT=127
 CONFIG_MTD=y
 CONFIG_DM_MTD=y
+CONFIG_DM_SERIAL=y
 CONFIG_MTD_NOR_FLASH=y
 CONFIG_SYS_FLASH_CFI_WIDTH_32BIT=y
 CONFIG_FLASH_SHOW_PROGRESS=0