nfp: standardize FW header whitespace

The nfp_net_ctrl.h file used spaces for indentation in the past but
tabs have crept in.  Host driver files use tabs for indentation by
default, so let's convert to tabs for consistency across the file
and our drivers.
Signed-off-by: Michael Rapson <michael.rapson@netronome.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>