Blackfin Serial Driver: fix bug - use mod_timer to replace only add_timer.
Blackfin Serial Driver: fix bug - use mod_timer to replace only add_timer.

http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=4045
If adding timer in both timer handler and rx interrupt, a timer may be
added when it is till in the pending list.

Signed-off-by: Sonic Zhang <c93d368f28096020dd845c4879a931e9d13ab23f@analog.com>
Signed-off-by: Bryan Wu <956b36c0f472d2edb239225c10f7e4411d1efbb9@kernel.org>


TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs