[PATCH] change add_timer to mod_timer

[PATCH] change add_timer to mod_timer

BZ: 34961

HSU driver might delete timer without sync in tasklet. The pending
timer might exist before next add_timer. It is better to use
mod_timer instead of add_timer.

Change-Id: I5762791f70a011b05e9e57d614a6e041ad27a400
Signed-off-by: Bin Yang <bin.yang@intel.com>
Reviewed-on: http://android.intel.com:8080/47762
Reviewed-by: Cai, Stanley W <stanley.w.cai@intel.com>
Reviewed-by: Kuppuswamy, Sathyanarayanan <sathyanarayanan.kuppuswamy@intel.com>
Tested-by: Wang, Zhifeng <zhifeng.wang@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>