MX5: Reuse the gd->tbl value for timestamp and add gd->lastinc for lastinc bss

The usage of bss values in drivers before initialisation of bss is forbidden.
In that special case some data in .rel.dyn gets corrupted.

This patch is the same as recently applied for arm926js architecture.

Signed-off-by: Stefano Babic <sbabic@denx.de>
CC: Heiko Schocher <hs@denx.de>