Blackfin: convert to use arch_gettimeoffset()

Convert Blackfin to use GENERIC_TIME via the arch_getoffset()
infrastructure, reducing the amount of arch specific code we need to
maintain.

I've taken my best swing at converting this, but I'm not 100% confident
I got it right.  My cross-compiler is now out of date (gcc4.2) so I
wasn't able to check if it compiled. Any assistance from arch
maintainers or testers to get this merged would be great.

Signed-off-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/Kconfig b/arch/blackfin/Kconfig
index 9a01d44..e519882 100644
--- a/arch/blackfin/Kconfig
+++ b/arch/blackfin/Kconfig
@@ -229,7 +229,7 @@
 
 config SMP
 	depends on BF561
-	select GENERIC_TIME
+	select GENERIC_CLOCKEVENTS
 	bool "Symmetric multi-processing support"
 	---help---
 	  This enables support for systems with more than one CPU,
@@ -613,12 +613,10 @@
 source kernel/Kconfig.hz
 
 config GENERIC_TIME
-	bool "Generic time"
-	default y
+	def_bool y
 
 config GENERIC_CLOCKEVENTS
 	bool "Generic clock events"
-	depends on GENERIC_TIME
 	default y
 
 choice
@@ -653,6 +651,10 @@
 	depends on GENERIC_CLOCKEVENTS
 	depends on !TICKSOURCE_GPTMR0
 
+config ARCH_USES_GETTIMEOFFSET
+	depends on !GENERIC_CLOCKEVENTS
+	def_bool y
+
 source kernel/time/Kconfig
 
 comment "Misc"