libertas: Improvements on automatic tx power control via SIOCSIWTXPOW (fixups)

This patch addresses comments from Dan Williams about the patch
committed as "libertas: Improvements on automatic tx power control via
SIOCSIWTXPOW."

Signed-off-by: Anna Neal <anna@cozybit.com>
Signed-off-by: Javier Cardona <javier@cozybit.com>
Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/libertas/cmd.c b/drivers/net/wireless/libertas/cmd.c
index aee19fa..a912fb6 100644
--- a/drivers/net/wireless/libertas/cmd.c
+++ b/drivers/net/wireless/libertas/cmd.c
@@ -1949,7 +1949,7 @@
 	cmd.hdr.size = cpu_to_le16(sizeof(cmd));
 	cmd.action = cpu_to_le16(CMD_ACT_SET);
 	cmd.enable = !!enable;
-	cmd.usesnr = !!enable;
+	cmd.usesnr = !!usesnr;
 	cmd.P0 = p0;
 	cmd.P1 = p1;
 	cmd.P2 = p2;