amd64_edac: Fix condition to verify max channels allowed for F15 M30h

The value returned from 'f15_m30h_determine_channel' will
always be 0x3 max. The condition

	(channel > 4 || channel < 0)

works as hardware never returns a value of 4, but
it leads to static checker analysis errors like
http://marc.info/?l=linux-edac&m=138607615131951&w=2.

Fix that.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>
Link: http://lkml.kernel.org/r/20131203130857.GA32170@elgon.mountain
[ Boris: massage commit message a bit. ]
Signed-off-by: Borislav Petkov <bp@suse.de>

drivers/edac/amd64_edac.c

@@ -1578,7 +1578,7 @@ static int f15_m30h_match_to_this_node(struct amd64_pvt *pvt, unsigned range,
 					     num_dcts_intlv, dct_sel);
 
 	/* Verify we stay within the MAX number of channels allowed */
-	if (channel > 4 || channel < 0)
+	if (channel > 3)
 		return -EINVAL;
 
 	leg_mmio_hole = (u8) (dct_cont_base_reg >> 1 & BIT(0));