ipmi: Fix a man page entry

The line was too long, and some of the entries were wrong (fur instead
of fru).  Just use the prop=val thing tha other entries use.
Signed-off-by: NCorey Minyard <cminyard@mvista.com>

qemu-options.hx

@@ -806,7 +806,7 @@ SRST
 
     Some drivers are:
 
-``-device ipmi-bmc-sim,id=id[,slave_addr=val][,sdrfile=file][,furareasize=val][,furdatafile=file][,guid=uuid]``
+``-device ipmi-bmc-sim,id=id[,prop[=value][,...]]``
     Add an IPMI BMC. This is a simulation of a hardware management
     interface processor that normally sits on a system. It provides a
     watchdog and the ability to reset and power control the system. You