mhi: devices: mhi_netdev: Print budget value for NAPI poll

Printing budget value with which NAPI poll is called helps
to identify if napi_complete() is getting called. Also reduce
the length of strings getting printed in the poll function.

Change-Id: Ic57bd0ce50dff3d3c874c7e0e2634c8351ff37cb
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>