arm: zynq: fix a bug in Zynq linker script

arm: zynq: fix a bug in Zynq linker script

Commit 41623c91 moved exception handlers to ".vectores" section
but it missed to adjust Zynq linker script.

Zynq boards hang up after relocation because "_start" symbol
does not point to the correct address and gd->relocaddr gets insane.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Michal Simek <monstr@monstr.eu>
Tested-by: Michal Simek <monstr@monstr.eu>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>