powerpc: Simplify and clean up the xmon terminal I/O

This factors out the common bits of arch/powerpc/xmon/start_*.c into
a new nonstdio.c, and removes some stuff that was supposed to make
xmon's I/O routines somewhat stdio-like but was never used.

It also makes the parsing of the xmon= command line option common,
so that ppc32 can now use xmon={off,on,early} also.

Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/xmon/nonstdio.h b/arch/powerpc/xmon/nonstdio.h
index 84211a2..47cebbd 100644
--- a/arch/powerpc/xmon/nonstdio.h
+++ b/arch/powerpc/xmon/nonstdio.h
@@ -1,22 +1,14 @@
-typedef int	FILE;
-extern FILE *xmon_stdin, *xmon_stdout;
 #define EOF	(-1)
-#define stdin	xmon_stdin
-#define stdout	xmon_stdout
-#define printf	xmon_printf
-#define fprintf	xmon_fprintf
-#define fputs	xmon_fputs
-#define fgets	xmon_fgets
-#define putchar	xmon_putchar
-#define getchar	xmon_getchar
-#define putc	xmon_putc
-#define getc	xmon_getc
-#define fopen(n, m)	NULL
-#define fflush(f)	do {} while (0)
-#define fclose(f)	do {} while (0)
-extern char *fgets(char *, int, void *);
-extern void xmon_printf(const char *, ...);
-extern void xmon_fprintf(void *, const char *, ...);
-extern void xmon_sprintf(char *, const char *, ...);
 
-#define perror(s)	printf("%s: no files!\n", (s))
+#define printf	xmon_printf
+#define putchar	xmon_putchar
+
+extern int xmon_putchar(int c);
+extern int xmon_getchar(void);
+extern char *xmon_gets(char *, int);
+extern void xmon_printf(const char *, ...);
+extern void xmon_map_scc(void);
+extern int xmon_expect(const char *str, unsigned long timeout);
+extern int xmon_write(void *ptr, int nb);
+extern int xmon_readchar(void);
+extern int xmon_read_poll(void);