lib: make lib/842 decompress functions static

Make the do_index and do_op functions static.

They are used only internally by the 842 decompression function,
and should be static.

Reported-By: Fengguang Wu <[e-mail]>
Signed-off-by: Fengguang Wu <[e-mail]>
Signed-off-by: Dan Streetman <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

lib/842/842_decompress.c

···
 	return 0;
 }
 
-int do_index(struct sw842_param *p, u8 n)
+static int do_index(struct sw842_param *p, u8 n)
 {
 	switch (n) {
 	case 2:
···
 	}
 }
 
-int do_op(struct sw842_param *p, u8 o)
+static int do_op(struct sw842_param *p, u8 o)
 {
 	int i, ret = 0;