Fix a few gcc warnings.

Noticed while building all of mpc8xx. Also
constify usage string in timer.c
Warnings fixed are:
timer.c: In function 'timer':
timer.c:189: warning: format not a string literal and no format arguments
timer.c:258: warning: format not a string literal and no format arguments
atm.c: In function 'atmUnload':
atm.c:99: warning: array subscript is above array bounds
atm.c: In function 'atmLoad':
atm.c:65: warning: array subscript is above array bounds
codec.c: In function 'codsp_write_pop_int':
codec.c:678: warning: array subscript is above array bounds
codec.c: In function 'codsp_write_cop_short':
codec.c:585: warning: array subscript is above array bounds
codec.c: In function 'codsp_write_sop_int':
codec.c:512: warning: array subscript is above array bounds

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
diff --git a/examples/standalone/timer.c b/examples/standalone/timer.c
index 834cc9a..8fd38b2 100644
--- a/examples/standalone/timer.c
+++ b/examples/standalone/timer.c
@@ -113,7 +113,7 @@
 
 void setPeriod (tid_8xx_cpmtimer_t *hwp, ulong interval);
 
-static char *usage = "\n[q, b, e, ?] ";
+static const char usage[] = "\n[q, b, e, ?] ";
 
 int timer (int argc, char * const argv[])
 {
@@ -186,7 +186,7 @@
 	/* clear all events */
 	*hwp->terp = (CPMT_EVENT_CAP | CPMT_EVENT_REF);
 
-	printf (usage);
+	puts(usage);
 	running = 0;
 	while ((c = getc()) != 'q') {
 	    if (c == 'b') {
@@ -255,7 +255,7 @@
 	    } else {
 		printf ("\nEnter: q - quit, b - start timer, e - stop timer, ? - get status\n");
 	    }
-	    printf (usage);
+	    puts(usage);
 	}
 	if (running) {
 		printf ("Stopping timer\n");