Provide MRC with a console printing callback function

Let memory initialization code use the coreboot romstage console. This
simplifies the code and makes sure that all output is available in
/sys/firmware/log.

The pei_data structure is modified to allow passing the console output
function pointer. Romstage console_tx_byte() is used for this purpose.

Change-Id: I722cfcb9ff0cf527c12cb6cac09d77ef17b588e0
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: http://review.coreboot.org/1823
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martin@se-eng.com>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>

src/arch/x86/lib/romstage_console.c

@@ -29,7 +29,7 @@
 #include <console/ne2k.h>
 #endif
 
-static void console_tx_byte(unsigned char byte)
+void console_tx_byte(unsigned char byte)
 {
 	if (byte == '\n')
 		console_tx_byte('\r');