net: pktgen: fix code style (WARNING: please, no space before tabs)

Fix checkpatch code style warnings:

  WARNING: please, no space before tabs
  #230: FILE: net/core/pktgen.c:230:
  +#define M_NETIF_RECEIVE ^I1^I/* Inject packets into stack */$

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250415112916.113455-3-ps.report@gmx.net


Signed-off-by: Paolo Abeni <pabeni@redhat.com>