ARM: pxa: Fix OneNAND SPL builds

The OneNAND SPL used on PXA is slightly obscure. Due to the OneNAND limitation,
where we have only the first 1KiB of the OneNAND available upon power-up as a
memory-mapped area, from which the CPU starts executing, we place only the most
essential code into this first 1KiB . This code copies the rest of the SPL into
SRAM and jumps to it. This code is stored in section .text.0 .

The rest of the SPL is stored in section .text.1 . When running the OBJCOPY on
the SPL, it will preserve only .text section, but the .text.0 and .text.1 are
stripped away from the result, thus making the SPL binary empty. The patch adds
additional -j parameters to the OBJCOPY for PXA during the SPL build, which will
preserve the .text.0 and .text.1 sections.

Moreover, this patch also adds missing functions into the .text.0 section, since
otherwise the PXA270 with 1KiB-window OneNAND won't be able to boot.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Tom Rini <trini@ti.com>