defconfig: Add a config for AM335x High Security EVM

Add a new defconfig file for the AM335x High Security EVM. This config
is specific for the case of memory device booting. Memory device booting
is handled separatly from peripheral booting on HS devices as the load
address changes.

This defconfig is the same as for the non-secure part, except for:
	CONFIG_TI_SECURE_DEVICE option set to 'y'
	CONFIG_ISW_ENTRY_ADDR updated for secure images.
	CONFIG_FIT_IMAGE_POST_PROCESS option set to 'y'
	CONFIG_SPL_FIT_IMAGE_POST_PROCESS option set to 'y'
	CONFIG_USE_TINY_PRINTF option set to 'y' to reduce SPL size
	CONFIG_SPL_SYS_MALLOC_SIMPLE set to 'y' to reduce SPL size

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>