cxgb4: Fix the -Wmisleading-indentation warning

Fix the gcc warning:

drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c:2673:9: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
 2673 |         for (i = 0; i < n; ++i) \
Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Link: https://lore.kernel.org/r/1604467444-23043-1-git-send-email-kaixuxia@tencent.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>