mhi: net: Reduce NAPI poll weight to 64 for debug builds

Reducing NAPI poll weight to 64 from 128 for debug builds.
The maximum frags previously it can accumlate for  SKB is 128,
which leads to stack overflow. So, will reduce max frags to skb
to 64.

Change-Id: Iec33c4e870f9bf3c601d72078992ccb2a0b458ec
Signed-off-by: Vivek Pernamitta <vpernami@codeaurora.org>