kvm tools: Fix virtio console input problem

term_getc only get one char at a time, so term_getc_iov should
send one char back to guest.

Otherwise, you will get four input chars when you only type one like bewlow:

sid login: r^@^@^@o^@^@^@o^@^@^@t^@^@^@

Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

term.c

@@ -71,9 +71,8 @@ int term_getc_iov(int who, struct iovec *iov, int iovcnt)
 		return 0;
 
 	*((int *)iov[0].iov_base)	= c;
-	iov[0].iov_len			= sizeof(int);
 
-	return sizeof(int);
+	return sizeof(char);
 }
 
 int term_putc_iov(int who, struct iovec *iov, int iovcnt)