clocksource: Kconfig: Let EM_TIMER_STI depend on HAS_IOMEM

In 'em_sti.c', it will call devm_ioremap_resource() which need
HAS_IOMEM. So need let EM_TIMER_STI depend on HAS_IOMEM, too.

The related error (with allmodconfig under score):

LD init/built-in.o
em_sti.c:(.text.em_sti_probe+0x84): undefined reference to `devm_ioremap_resource'
make: *** [vmlinux] Error 1

Signed-off-by: Chen Gang <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>

drivers/clocksource/Kconfig

···
 
 config EM_TIMER_STI
 	bool "Renesas STI timer driver" if COMPILE_TEST
-	depends on GENERIC_CLOCKEVENTS
+	depends on GENERIC_CLOCKEVENTS && HAS_IOMEM
 	default SYS_SUPPORTS_EM_STI
 	help
 	  This enables build of a clocksource and clockevent driver for