At some places, the log2() function is used despite this function
works on float. This introduces a dependency to the math lib but
most of the time it is not required because we want an integer log2.
Add a new helper to do this job and fix nfp driver.
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Alejandro Lucero <alejandro.lucero@netronome.com>