Input: hp_sdc_rtc should depend on serio

Fix this build error when CONFIG_SERIO is not set
hp_sdc_rtc.c:691: undefined reference to `hp_sdc_request_timer_irq'
and so on..

"select should be used with care. select will force
a symbol to a value without visiting the dependencies."
Signed-off-by: Alexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/misc/Kconfig

@@ -214,7 +214,7 @@ config INPUT_SGI_BTNS
 
 config HP_SDC_RTC
 	tristate "HP SDC Real Time Clock"
-	depends on GSC || HP300
+	depends on (GSC || HP300) && SERIO
 	select HP_SDC
 	help
 	  Say Y here if you want to support the built-in real time clock