beaglebone_defconfig: use u-boot 2013.04, add comments

# architecture

BR2_arm=y

BR2_cortex_a8=y

BR2_EXTRA_GCC_CONFIG_OPTIONS="--with-fpu=vfpv3 --with-float=hard"

# BR2_SOFT_FLOAT is not set

# system

BR2_TARGET_GENERIC_HOSTNAME="beaglebone"

BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_DEVTMPFS=y

BR2_TARGET_GENERIC_GETTY_PORT="ttyO0"

# BR2_TARGET_GENERIC_REMOUNT_ROOTFS_RW is not set

# filesystem

BR2_TARGET_ROOTFS_EXT2=y

# BR2_TARGET_ROOTFS_TAR is not set

# Lock down headers to avoid breaking with new defaults

# lock down headers to avoid breaking with new defaults

BR2_KERNEL_HEADERS_VERSION=y

BR2_DEFAULT_KERNEL_VERSION="3.2.9"

# bootloader

BR2_TARGET_UBOOT=y

BR2_TARGET_UBOOT_BOARDNAME="am335x_evm"

BR2_TARGET_UBOOT_2012_10=y

BR2_TARGET_UBOOT_2013_04=y

BR2_TARGET_UBOOT_FORMAT_IMG=y

BR2_TARGET_UBOOT_SPL=y

BR2_TARGET_UBOOT_SPL_NAME="MLO"

# kernel

BR2_LINUX_KERNEL=y

BR2_LINUX_KERNEL_CUSTOM_GIT=y

BR2_LINUX_KERNEL_CUSTOM_GIT_REPO_URL="git://github.com/koenkooi/linux.git"