arm: Update linker scripts to ensure appended device tree is aligned

arm: Update linker scripts to ensure appended device tree is aligned

With commit 0535e46d55d7 ("scripts/dtc: Update to upstream version
v1.7.2-35-g52f07dcca47c") it is now a fatal error to U-Boot if our
device tree is not 8-byte aligned. In commit 85f586035d75 ("ARM: OMAP2+:
Pad SPL binary to 8-byte alignment before DTB") Beleswar Padhi explains
that we must have ALIGN(x) statements inside of a section to ensure that
padding is included and not simply that the linker address counter is
incremented. To that end, this patch:
- Expands some linker sections to be more readable when adding a second
  statement to the section.
- Aligns the final section before _end (for U-Boot) or
  _image_binary_end or __bss_end (for xPL phases) by 8-bytes by adding
  '. = ALIGN(8);' to the final section before the symbol.
- Ensure that we do have alignment by adding an ASSERT so that when not
  aligned we fail to link (and explain why).
- Remove now-spurious  '. = ALIGN(x);' statements that were intended to
  provide the above alignments.

Tested-by: Michal Simek <michal.simek@amd.com> # Zynq
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
[trini: Also update arch/arm/cpu/armv8/u-boot.lds as Ilas requested]
Signed-off-by: Tom Rini <trini@konsulko.com>