warp7: configs: add bl33 defconfig

warp7: configs: add bl33 defconfig

Add default configuration to run u-boot as BL33 in the ARM Trusted Firmware
boot flow for AArch32 case.

Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Lukasz Majewski <lukma@denx.de>
Cc: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Cc: u-boot@lists.denx.de