MLK-13450-7 mx7ulp: Add M4 core boot support when using single boot mode

MLK-13450-7 mx7ulp: Add M4 core boot support when using single boot mode

The single boot mode in MX7ULP will only boot up A7, the M4 is running in ROM
by checking entry from SIM0 GP register.

In this patch, We bind M4 image with u-boot.bin by allocating a section for m4 image.
So the whole image (included M4 image) will be loaded by A7 ROM into DDR. Then
when u-boot is up, it will try to load M4 image into TCML and boot it there.

Since M4 image will not be relocated in u-boot codes, we must load it during
board_f. Current implementation put it in arch_cpu_init to get M4 booted
as quick as possible.

We requires the M4 image with IVT head and padding embedded, not a RAW binary. The
image should be same as what is used for M4 QSPI boot in dual boot mode.

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit 04163dbd4f6190f310fff17b53b4bc7b8370ba89)