[POWERPC] Early serial debug support for PPC44x

This adds support for early serial debugging via the built in
port on IBM/AMCC PowerPC 44x CPUs.  It uses a bolted TLB entry in
address space 1 for the UART's mapping, allowing robust debugging both
before and after the initialization of the MMU.

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/udbg.c

@@ -51,6 +51,9 @@ void __init udbg_early_init(void)
 	udbg_init_pas_realmode();
 #elif defined(CONFIG_BOOTX_TEXT)
 	udbg_init_btext();
+#elif defined(CONFIG_PPC_EARLY_DEBUG_44x)
+	/* PPC44x debug */
+	udbg_init_44x_as1();
 #endif
 }