powerpc/rtas: Fix spelling mistake "Discharching" -> "Discharging"

Trivial fix to spelling mistake in battery_charging array.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/rtas-proc.c

@@ -528,7 +528,7 @@ static void ppc_rtas_process_sensor(struct seq_file *m,
 		"EPOW power off" };
 	const char * battery_cyclestate[]  = { "None", "In progress", 
 						"Requested" };
-	const char * battery_charging[]    = { "Charging", "Discharching", 
+	const char * battery_charging[]    = { "Charging", "Discharging",
 						"No current flow" };
 	const char * ibm_drconnector[]     = { "Empty", "Present", "Unusable", 
 						"Exchange" };