mb/libretrend/lt1000: Add Libretrend LT1000 mainboard

Change-Id: I32fc8a7d3177ba379d04ad8b87adefcfca2b0fab
Signed-off-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/30360
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>

configs/config.libretrend_lt1000

@@ -0,0 +1,5 @@
+CONFIG_VENDOR_LIBRETREND=y
+CONFIG_POWER_STATE_OFF_AFTER_FAILURE=y
+CONFIG_GENERIC_LINEAR_FRAMEBUFFER=y
+CONFIG_USER_TPM2=y
+CONFIG_SEABIOS_ADD_SERCON_PORT_FILE=y