ethtool: fix up dump_coalesce output to match actual option names

When the coalesce settings are printed with --show-coalesce a few of the
option names lack the pluralization that is present in the man page and
usage info, but are otherwise identical.

This inconsistency could lead to some confusion if a user attempts to set
the coalesce settings by matching the output they see from --show-coalesce,
so fix this.

Signed-off-by: Nicholas Nunley <nicholas.d.nunley@intel.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/ethtool.c b/ethtool.c
index d1b82f0..8fbb4bd 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -1420,14 +1420,14 @@
 		"tx-frames-irq: %u\n"
 		"\n"
 		"rx-usecs-low: %u\n"
-		"rx-frame-low: %u\n"
+		"rx-frames-low: %u\n"
 		"tx-usecs-low: %u\n"
-		"tx-frame-low: %u\n"
+		"tx-frames-low: %u\n"
 		"\n"
 		"rx-usecs-high: %u\n"
-		"rx-frame-high: %u\n"
+		"rx-frames-high: %u\n"
 		"tx-usecs-high: %u\n"
-		"tx-frame-high: %u\n"
+		"tx-frames-high: %u\n"
 		"\n",
 		ecoal->stats_block_coalesce_usecs,
 		ecoal->rate_sample_interval,