mhi: devices: mhi_netdev: Update napi poll weight to 128

Increasing napi poll weight to 128 helps processing OOB
sooner. This reduces the napi schedule overhead if number
of outstanding events are higher and OOB event is posted
later in the pending list of events.

Change-Id: Ia51fcef7ded560e1986a1e6d80fdd162df7c1903
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>