OMAP: Timer: Replace bss variable by gd

OMAP: Timer: Replace bss variable by gd

Reuse the gd->tbl value for timestamp and add gd->lastinc for lastinc bss
values in the OMAP timer driver.

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

Signed-off-by: Dirk Behme <dirk.behme@gmail.com>
Tested-by: Steve Sakoman <steve.sakoman@linaro.org>
Tested-by: John Rigby <john.rigby@linaro.org>
Tested-by: Nishanth Menon <nm@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
Tested-by: Heiko Schocher <hs@denx.de>
Tested-by: Sandeep Paulraj <s-paulraj@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>