net: rmnet_data: Further optimize UL aggregation accumulation

Do not aggregate frames if they are sapced out more than 10ms. Since the
scedule_delayed_work() API only takes time in jiffies, ping packets
are getting substantially delayed. Instead, just send them. This parameter
is tunable from the module parameters location.

CRs-Fixed: 772705
Change-Id: I6ac337c8d61b1290f939b86081070c14c2c757b1
Signed-off-by: Harout Hedeshian <harouth@codeaurora.org>