u-boot: Add veyron minnie chromebook configs

This adds U-Boot configuration for the ASUS Chromebook Flip C100PA, also
known as "chromebook_minnie" in the U-Boot upstream defconfigs. It uses
the shared tree for the "veyron" baseboard. The config is almost the
same as upstream defconfig, but with REMAKE_ELF and POSITION_INDEPENDENT
enabled.

Untested since I don't have the veyron minnie chromebook.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>

resources/u-boot/veyron_minnie/board.cfg

+ubtree="veyron"
+arch="ARMv7"