CONFIG_ENV_ADDR helps in picking environment from flash before DDR init.
The macro value is already defined in ls1046ardb_tfa_defconfig, also
define the value as 0x40300000 in qspi_defconfig.
ls1046aqds has one spansion flash "S25FL128S_64K" of size 16M with
sector size 64K. Correct ENV_ADDR and ENV_SECT_SIZE value for QSPI and
TFA defconfigs of the board.