CRISv32: use MMIO clocksource

Use a generic MMIO clocksource and get rid of some lines of code.

Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Jesper Nilsson <jespern@axis.com>
diff --git a/arch/cris/Kconfig b/arch/cris/Kconfig
index 366dc83..bd920cc 100644
--- a/arch/cris/Kconfig
+++ b/arch/cris/Kconfig
@@ -55,6 +55,7 @@
 	select IRQ_DOMAIN if ETRAX_ARCH_V32
 	select OF if ETRAX_ARCH_V32
 	select OF_EARLY_FLATTREE if ETRAX_ARCH_V32
+	select CLKSRC_MMIO if ETRAX_ARCH_V32
 	select GENERIC_CLOCKEVENTS if ETRAX_ARCH_V32
 
 config HZ