[patch] ipmi: make static checkers happy about range checks

[Dan Carpenter <error27@gmail.com>]

I'm working on a Smatch check that complains that addr->channel comes
from the user and it might be negative.  It actually can *not* be
negative because we already checked that when we called
ipmi_validate_addr() from handle_send_req().  Also it can't be greater
than or equal to IPMI_MAX_CHANNELS because we already verified that as
well.

Although this change doesn't do anything, it's still a cleanup because
it makes the checking consistent and also it silences the static
analysis warnings.

Signed-off-by: Dan Carpenter <error27@gmail.com>
---
Really, I would prefer to just make ->channel unsigned but the type
comes from the IPMI spec.

diff --git a/drivers/char/ipmi/ipmi_msghandler.c b/drivers/char/ipmi/ipmi_msghandler.c
index 4f3f8c9..57f4c80 100644
--- a/drivers/char/ipmi/ipmi_msghandler.c
+++ b/drivers/char/ipmi/ipmi_msghandler.c
@@ -1527,7 +1527,7 @@ static int i_ipmi_request(ipmi_user_t          user,
 		long                  seqid;
 		int                   broadcast = 0;
 
-		if (addr->channel >= IPMI_MAX_CHANNELS) {
+		if (addr->channel < 0 || addr->channel >= IPMI_MAX_CHANNELS) {
 			ipmi_inc_stat(intf, sent_invalid_commands);
 			rv = -EINVAL;
 			goto out_err;
@@ -1657,7 +1657,7 @@ static int i_ipmi_request(ipmi_user_t          user,
 		unsigned char         ipmb_seq;
 		long                  seqid;
 
-		if (addr->channel >= IPMI_MAX_CHANNELS) {
+		if (addr->channel < 0 || addr->channel >= IPMI_MAX_CHANNELS) {
 			ipmi_inc_stat(intf, sent_invalid_commands);
 			rv = -EINVAL;
 			goto out_err;
@@ -1797,7 +1797,7 @@ static int check_addr(ipmi_smi_t       intf,
 		      unsigned char    *saddr,
 		      unsigned char    *lun)
 {
-	if (addr->channel >= IPMI_MAX_CHANNELS)
+	if (addr->channel < 0 || addr->channel >= IPMI_MAX_CHANNELS)
 		return -EINVAL;
 	*lun = intf->channels[addr->channel].lun;
 	*saddr = intf->channels[addr->channel].address;