tracing: stop making gpio tracing configurable

gpio tracing was made configurable in 4.4-rc1 (commit ddd70280bf
("tracing: gpio: Add Kconfig option for enabling/disabling trace
events")). Since then it is the only event type that can be compiled
conditionally. Given that there is only little overhead I don't
understand the reasoning and I was annoyed more than once that gpio
events were not available without recompiling.

So drop the Kconfig symbol and make gpio events available
unconditionally.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

kernel/trace/Kconfig

@@ -774,13 +774,6 @@ config TRACE_EVAL_MAP_FILE
 
 	If unsure, say N
 
-config TRACING_EVENTS_GPIO
-	bool "Trace gpio events"
-	depends on GPIOLIB
-	default y
-	help
-	  Enable tracing events for gpio subsystem
-
 config GCOV_PROFILE_FTRACE
 	bool "Enable GCOV profiling on ftrace subsystem"
 	depends on GCOV_KERNEL