work around ERR11115:
The lower part of the OCRAM is unusable on i.MX6UL mask revision 2N52P
with date code before 9/22/2017. Adjust CONFIG_SPL_TEXT_BASE and
CONFIG_SPL_MAX_SIZE accordingly to fix boot on these SoCs.
Signed-off-by: Max Merchel <Max.Merchel@ew.tq-group.com>