[PATCHv5][ 4/7] board: tbs2910_defconfig: Add support for booting general purpose distributions

[Denis 'GNUtoo' Carikli]

This is needed to enable distro_boot support later on.

Adding the necessary configuration to enable booting general
purpose distributions is typically done by enabling
CONFIG_DISTRO_DEFAULTS.

However the resulting image size is is already very close to
the size limit and PXE isn't strictly needed, so instead we
made sure that all the configuration selected by
CONFIG_DISTRO_DEFAULTS were selected, with the exception of
PXE related configuration (CONFIG_BOOTP_PXE and
CONFIG_CMD_PXE) that are both disabled.

With arm-linux-gnueabi-gcc 9.3.0-1 from the Parabola
GNU/Linux distribution, we have the following size
differences:
- text: +7526 bytes
- data: +28 bytes
- bss: -12 bytes
- total: +7542 bytes

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo at cyberdimension.org>
---
Changelog since v4:
-------------------
- As requested, I Added in the commit message the reason why the
  change is really needed as the short summary is not self
  explanatory enough.
- Fixed a typo in the commit message
  (resultimg image instead of resulting image).
- Switched to the use of CONFIG_CMD_SYSBOOT instead of
  CONFIG_DISTRO_BOOTCMD as suggested
  The only changes between the two resulting .config are the following:
  -CONFIG_DISTRO_DEFAULTS=y
  +# CONFIG_DISTRO_DEFAULTS is not set
  -CONFIG_BOOTP_PXE=y
  -CONFIG_BOOTP_PXE_CLIENTARCH=0x15
  -CONFIG_CMD_PXE=y
  +# CONFIG_CMD_PXE is not set
---
 configs/tbs2910_defconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/configs/tbs2910_defconfig b/configs/tbs2910_defconfig
index d14ff45615..fc9095c859 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -9,6 +9,7 @@ CONFIG_NR_DRAM_BANKS=1
 CONFIG_PRE_CON_BUF_ADDR=0x7c000000
 CONFIG_CMD_HDMIDETECT=y
 CONFIG_AHCI=y
+CONFIG_ENV_VARS_UBOOT_CONFIG=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTCOMMAND=y
 CONFIG_BOOTCOMMAND="mmc rescan; if run bootcmd_up1; then run bootcmd_up2; else run bootcmd_mmc; fi"
@@ -43,6 +44,7 @@ CONFIG_CMD_MII=y
 CONFIG_CMD_PING=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_TIME=y
+CONFIG_CMD_SYSBOOT=y
 CONFIG_CMD_EXT2=y
 CONFIG_CMD_EXT4=y
 CONFIG_CMD_EXT4_WRITE=y
-- 
2.26.2