stm32mp1: update memory layout

stm32mp1: update memory layout

Update the memory layout to be aligned with other platform and avoid
overlap with 32MB Linux kernel (multiv7 image).
+ Kernel => 32MiB offset = 0xC2000000
            and increase the bootm size to 32MiB
+ FDT => 64MiB offset = 0xc4000000
+ SCRIPT => 65Mib offset = 0xc4100000
+ PXESCRIPT => 66Mib offset = 0xc4200000
+ SPLASHIMAGE => 67Mib offset = 0xc4300000
+ RAMDISK => 68Mib offset = 0xc4400000
             (not limited size)

In sources/boot/u-boot/doc/README.distro

+ kernel_addr_r: A size of 16MB for the kernel is likely adequate.
+ pxefile_addr_r: A size of 1MB for extlinux.conf is more than adequate.
+ fdt_addr_r: A size of 1MB for the FDT/DTB seems reasonable.
+ ramdisk_addr_r: It is recommended that this location be highest in RAM
                  out of fdt_addr_, kernel_addr_r, and ramdisk_addr_r,
                  so that the RAM disk can vary in size and use any
                 available RAM.
+ pxefile_addr_r: A size of 1MB for extlinux.conf is more than adequate.
+ scriptaddr: A size of 1MB for extlinux.conf is more than adequate.

For suggestions on memory locations for ARM systems, you must follow
the guidelines specified in Documentation/arm/Booting
in the Linux kernel tree.

And in sources/linux-stm32mp/Documentation/arm/Booting

The zImage may also be placed in system RAM and called there.  The
kernel should be placed in the first 128MiB of RAM.  It is recommended
that it is loaded above 32MiB in order to avoid the need to relocate
prior to decompression, which will make the boot process slightly
faster.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>