init/Kconfig: Hide printk log config if CONFIG_PRINTK=n

commit 361e9dfb upstream.

The buffers sized by CONFIG_LOG_BUF_SHIFT and
CONFIG_LOG_CPU_MAX_BUF_SHIFT do not exist if CONFIG_PRINTK=n, so don't
ask about their size at all.
Signed-off-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
[bwh: Backported to 3.2: drop change to CONFIG_LOG_CPU_MAX_BUF_SHIFT]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

init/Kconfig

@@ -555,6 +555,7 @@ config LOG_BUF_SHIFT
 	int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
 	range 12 21
 	default 17
+	depends on PRINTK
 	help
 	  Select kernel log buffer size as a power of 2.
 	  Examples: