[linux] Fix console output on big-endian targets

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/interface/linux/linux_console.c

diff --git a/src/interface/linux/linux_console.c b/src/interface/linux/linux_console.c
index d5415b6..79a9c4b 100644
--- a/src/interface/linux/linux_console.c
+++ b/src/interface/linux/linux_console.c
@@ -43,8 +43,10 @@
 
 static void linux_console_putchar(int c)
 {
+	char ch = c;
+
 	/* write to stdout */
-	if (linux_write(1, &c, 1) != 1)
+	if (linux_write(1, &ch, sizeof (ch)) != 1)
 		DBG("linux_console write failed (%s)\n", linux_strerror(linux_errno));
 }