[PATCH] powerpc: udbg updates

The udbg low level io layer has an issue with udbg_getc() returning a
char (unsigned on ppc) instead of an int, thus the -1 if you had no
available input device could end up turned into 0xff, filling your
display with bogus characters. This fixes it, along with adding a little
blob to xmon to do a delay before exiting when getting an EOF and fixing
the detection of ADB keyboards in udbg_adb.c

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/udbg_16550.c b/arch/powerpc/kernel/udbg_16550.c
index 28a58da..e58c048 100644
--- a/arch/powerpc/kernel/udbg_16550.c
+++ b/arch/powerpc/kernel/udbg_16550.c
@@ -69,14 +69,14 @@
 	return -1;
 }
 
-static char udbg_550_getc(void)
+static int udbg_550_getc(void)
 {
 	if (udbg_comport) {
 		while ((in_8(&udbg_comport->lsr) & LSR_DR) == 0)
 			/* wait for char */;
 		return in_8(&udbg_comport->rbr);
 	}
-	return 0;
+	return -1;
 }
 
 void udbg_init_uart(void __iomem *comport, unsigned int speed,