msm: rndis_ipa: add ability to enable/disable uplink de-aggregation

This change adds the ability to enable/disable the uplink
de-aggregation. the enable/disable is done by changing
the debugfs entry called <debugfs>/rndis_ipa/deaggregation_enable.
The default value is set to enabled.

Change-Id: I1f4cbf3e6888bc9fb3ddd63d2987b256eccc4755
Signed-off-by: Talel Shenhar <stalel@codeaurora.org>
Signed-off-by: Gidon Studinski <gidons@codeaurora.org>