[PATCH] coverity: ipmi: avoid overrun of ipmi_interfaces[]

Fix overrun of static array "ipmi_interfaces" of size 4 at position 4 with
index variable "if_num".

Definitions involved:
297  	#define MAX_IPMI_INTERFACES 4
298  	static ipmi_smi_t ipmi_interfaces[MAX_IPMI_INTERFACES];

Signed-off-by: Zaur Kambarov <zkambarov@coverity.com>
Cc: Corey Minyard <minyard@acm.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>