ARMv8: add GOT sections to the list of sections copied

Recent Linux distributions (e.g. Debian 9) include cross-compilers for
AArch64, but only for the aarch64-linux-gnu triplet only. It can thus
be expected that users will attempt to use the system cross-compiler
(instead of an aarch64-elf variant) to compile U-Boot for their ARMv8
target systems.

One key differences between an aarch64-linux-gnu and an aarch64-elf
compiler are the default settings regarding position-independent: with
the aarch64-linux-gnu compiler, the default will create and use the
global offset table.

This change-set adjusts the list of sections copied on ARMv8 to include
the GOT sections. With this added, the list matches the previous setup
for AArch32 closely.

Note that this is not an 'academic' issue, but was in fact encountered
by our QA during testing of the RK3399-Q7 BSP and resulted in an
early failure of the SPL stage during FDT setup.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>