chore: add beaglebone green eco in build guides

New platform beaglebone green ECO board is supported in 11.02
release, so add DT file and u-boot defconfig in build guides
to build for this board.

Signed-off-by: Judith Mendez <[email protected]>

Author: jmenti

source/linux/Foundational_Components/Kernel/_Users_Guide.rst

@@ -310,6 +310,8 @@ Compiling the Device Tree Binaries
     +===========================================+======================================+
     | Beaglebone Black                          | am335x-boneblack.dts                 |
     +-------------------------------------------+--------------------------------------+
+    | Beaglebone Green ECO                      | am335x-bonegreen-eco.dts             |
+    +-------------------------------------------+--------------------------------------+
     | AM335x General Purpose EVM                | am335x-evm.dts                       |
     +-------------------------------------------+--------------------------------------+
     | AM335x Starter Kit                        | am335x-evmsk.dts                     |

source/linux/Foundational_Components/U-Boot/BG-Build-OMAP.rst

@@ -81,6 +81,8 @@ with:
 +----------------------------+-----------------------------+--------------------------+----------------------------------------------+--------------------------+--------------------------+--------------------------+-----------------------------------------+------------------------------------------+
 | AM335x ICE                 | ``am335x_evm_defconfig``    |                          |                                              | ``am335x_evm_defconfig`` |                          |                          |                                         |                                          |
 +----------------------------+-----------------------------+--------------------------+----------------------------------------------+--------------------------+--------------------------+--------------------------+-----------------------------------------+------------------------------------------+
+| BeagleBone Green ECO       | ``am335x_evm_defconfig``    | ``am335x_evm_defconfig`` |                                              | ``am335x_evm_defconfig`` |                          |                          |                                         |                                          |
++----------------------------+-----------------------------+--------------------------+----------------------------------------------+--------------------------+--------------------------+--------------------------+-----------------------------------------+------------------------------------------+
 | BeagleBone Black           | ``am335x_evm_defconfig``    | ``am335x_evm_defconfig`` |                                              | ``am335x_evm_defconfig`` |                          |                          |                                         |                                          |
 +----------------------------+-----------------------------+--------------------------+----------------------------------------------+--------------------------+--------------------------+--------------------------+-----------------------------------------+------------------------------------------+
 | BeagleBone White           | ``am335x_evm_defconfig``    |                          |                                              | ``am335x_evm_defconfig`` |                          |                          |                                         |                                          |