mfd: Align ab8500 with the abx500 interface

This patch makes the ab8500 mixed signal chip expose the same
interface for register access as the ab3100, ab3550 and ab5500 chip.
The ab8500_read() and ab8500_write() is removed and replaced with
abx500_get_register_interruptible() and
abx500_set_register_interruptible().

Signed-off-by: Mattias Wallin <mattias.wallin@stericsson.com>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 8a463e6..ec0af47 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -434,7 +434,7 @@
 
 config ABX500_CORE
 	bool "ST-Ericsson ABX500 Mixed Signal Circuit register functions"
-	default y if ARCH_U300
+	default y if ARCH_U300 || ARCH_U8500
 	help
 	  Say yes here if you have the ABX500 Mixed Signal IC family
 	  chips. This core driver expose register access functions.
@@ -475,7 +475,7 @@
 
 config AB8500_CORE
 	bool "ST-Ericsson AB8500 Mixed Signal Power Management chip"
-	depends on SPI=y && GENERIC_HARDIRQS
+	depends on SPI=y && GENERIC_HARDIRQS && ABX500_CORE
 	select MFD_CORE
 	help
 	  Select this option to enable access to AB8500 power management