ARM: imx: clean and consolidate imx5 suspend and idle code

The imx5 idle code that existed in mm-imx5.c is moved to pm-imx5.c.
The imx5_pm_init call is now exported and called during the
MACHINE_START late_init in supported imx5 platforms.

Remove various enabling/disabling of the gpc_dvfs clock and
enable it once during initialization.  This is a very low
power clock that must be enabled during low power operations.

There are only two "suspend_state_t" imx5 low power modes ever
used.  STOP_POWER_OFF for suspend to mem and
WAIT_UNCLOCKED_POWER_OFF for idle and suspend to standby.  The
latter mode only requires 500 nanoseconds of extra hardware
exit time beyond a basic WFI operation (WAIT_CLOCKED mode) so
no other idle mode is necessary.  Given this information, it
is more efficient to keep the registers in the often used
WAIT_UNCLOCKED_POWER_OFF state and only to and from the
STOP_POWER_OFF register state as needed when suspend to
mem is required.

Signed-off-by: Robert Lee <rob.lee@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
diff --git a/arch/arm/plat-mxc/include/mach/common.h b/arch/arm/plat-mxc/include/mach/common.h
index cf663d8..f65d068 100644
--- a/arch/arm/plat-mxc/include/mach/common.h
+++ b/arch/arm/plat-mxc/include/mach/common.h
@@ -95,7 +95,6 @@
 };
 
 extern void mx3_cpu_lp_set(enum mx3_cpu_pwr_mode mode);
-extern void mx5_cpu_lp_set(enum mxc_cpu_pwr_mode mode);
 extern void imx_print_silicon_rev(const char *cpu, int srev);
 
 void avic_handle_irq(struct pt_regs *);
@@ -146,8 +145,10 @@
 
 #ifdef CONFIG_PM
 extern void imx6q_pm_init(void);
+extern void imx51_pm_init(void);
 #else
 static inline void imx6q_pm_init(void) {}
+static inline void imx51_pm_init(void) {}
 #endif
 
 #ifdef CONFIG_NEON