tty: n_gsm, remove duplicates of parameters

dp, f, and i are only duplicates of gsmld_receive_buf's parameters. Use
the parameters directly (cp, fp, and count) and delete these local
variables.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210302062214.29627-41-jslaby@suse.czSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/n_gsm.c

@@ -2416,27 +2416,24 @@ static void gsmld_receive_buf(struct tty_struct *tty, const unsigned char *cp,
 			      char *fp, int count)
 {
 	struct gsm_mux *gsm = tty->disc_data;
-	const unsigned char *dp;
-	char *f;
-	int i;
 	char flags = TTY_NORMAL;
 
 	if (debug & 4)
 		print_hex_dump_bytes("gsmld_receive: ", DUMP_PREFIX_OFFSET,
 				     cp, count);
 
-	for (i = count, dp = cp, f = fp; i; i--, dp++) {
-		if (f)
-			flags = *f++;
+	for (; count; count--, cp++) {
+		if (fp)
+			flags = *fp++;
 		switch (flags) {
 		case TTY_NORMAL:
-			gsm->receive(gsm, *dp);
+			gsm->receive(gsm, *cp);
 			break;
 		case TTY_OVERRUN:
 		case TTY_BREAK:
 		case TTY_PARITY:
 		case TTY_FRAME:
-			gsm_error(gsm, *dp, flags);
+			gsm_error(gsm, *cp, flags);
 			break;
 		default:
 			WARN_ONCE(1, "%s: unknown flag %d\n",