bootconfig: Fix CONFIG_BOOTTIME_TRACING dependency issue

Since commit d8a953dd ("bootconfig: Set CONFIG_BOOT_CONFIG=n by
default") also changed the CONFIG_BOOTTIME_TRACING to select
CONFIG_BOOT_CONFIG to show the boot-time tracing on the menu,
it introduced wrong dependencies with BLK_DEV_INITRD as below.

WARNING: unmet direct dependencies detected for BOOT_CONFIG
  Depends on [n]: BLK_DEV_INITRD [=n]
  Selected by [y]:
  - BOOTTIME_TRACING [=y] && TRACING_SUPPORT [=y] && FTRACE [=y] && TRACING [=y]

This makes the CONFIG_BOOT_CONFIG selects CONFIG_BLK_DEV_INITRD to
fix this error and make CONFIG_BOOTTIME_TRACING=n by default, so
that both boot-time tracing and boot configuration off but those
appear on the menu list.

Link: http://lkml.kernel.org/r/158264140162.23842.11237423518607465535.stgit@devnote2

Fixes: d8a953dd ("bootconfig: Set CONFIG_BOOT_CONFIG=n by default")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Compiled-tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

init/Kconfig

@@ -1217,7 +1217,7 @@ endif
 
 config BOOT_CONFIG
 	bool "Boot config support"
-	depends on BLK_DEV_INITRD
+	select BLK_DEV_INITRD
 	help
 	  Extra boot config allows system admin to pass a config file as
 	  complemental extension of kernel cmdline when booting.

kernel/trace/Kconfig

@@ -145,7 +145,6 @@ config BOOTTIME_TRACING
 	bool "Boot-time Tracing support"
 	depends on TRACING
 	select BOOT_CONFIG
-	default y
 	help
 	  Enable developer to setup ftrace subsystem via supplemental
 	  kernel cmdline at boot time for debugging (tracing) driver