This commit avoids generating ./SPL twice.
- Fist time descending to spl/
- Second time as a prerequisite of u-boot-with-spl.imx,
u-boot-with-nand-spl.imx.
#
# (C) Copyright 2002
# Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
#
# SPDX-License-Identifier: GPL-2.0+
#
# Make ARMv5 to allow more compilers to work, even though its v6.
PLATFORM_CPPFLAGS += -march=armv5