skiboot: Fix comment around OPAL_IMC_COUNTERS_ enum

Fixes: 7801be0 ('skiboot: Add opal calls to init/start/stop IMC devices)
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

include/opal-api.h

@@ -1248,7 +1248,7 @@ enum {
 	XIVE_DUMP_EMU_STATE	= 5,
 };
 
-/* Operation argument to IMC Microcode */
+/* "type" argument options for OPAL_IMC_COUNTERS_* calls */
 enum {
 	OPAL_IMC_COUNTERS_NEST = 1,
 	OPAL_IMC_COUNTERS_CORE = 2,