Fix hosted glibc backtrace

According to backtrace(3) man page, the string returned from
backtrace_symbols() contains the return address so we shouldn't
need to print it ourselves.

Change-Id: Ia779207285c9ea0052b9aee3d84ee8380bf46d82

firmware/target/hosted/backtrace-glibc.c

@@ -52,7 +52,7 @@ void rb_backtrace(int pc, int sp, unsigned *line)
 
     for(int i = 0; i < count; i++)
     {
-        lcd_putsf(0, (*line)++, "  %s", buffer[i], strings[i]);
+        lcd_putsf(0, (*line)++, "  %s", strings[i]);
         lcd_update();
     }