clocksource: convert ARM 32-bit down counting clocksources

Convert SP804, MXC, Nomadik and Orion 32-bit down-counting clocksources
to generic mmio clocksource infrastructure.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Lennert Buytenhek <kernel@wantstofly.org>
Acked-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 9aa5514..0a05a57 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1042,6 +1042,7 @@
 
 config PLAT_ORION
 	bool
+	select CLKSRC_MMIO
 	select HAVE_SCHED_CLOCK
 
 config PLAT_PXA
@@ -1052,6 +1053,7 @@
 
 config ARM_TIMER_SP804
 	bool
+	select CLKSRC_MMIO
 
 source arch/arm/mm/Kconfig