ARM: OMAP2/3: PRM: add SoC reset functions (using the CORE DPLL method)

Add SoC reset functions into the PRM code.  These functions are based
on code from mach-omap2/prcm.c.  They reset the SoC using the CORE DPLL
reset method (as opposed to one of the other two or three chip reset
methods).

Adding them here will facilitate their removal from
arch/arm/mach-omap2/prcm.c.  (prcm.c is deprecated.)

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Tested-by: Vaibhav Hiremath <hvaibhav@ti.com>
diff --git a/arch/arm/mach-omap2/prm2xxx.h b/arch/arm/mach-omap2/prm2xxx.h
index 1d97112..fe8a14f 100644
--- a/arch/arm/mach-omap2/prm2xxx.h
+++ b/arch/arm/mach-omap2/prm2xxx.h
@@ -124,6 +124,8 @@
 extern int omap2xxx_clkdm_sleep(struct clockdomain *clkdm);
 extern int omap2xxx_clkdm_wakeup(struct clockdomain *clkdm);
 
+extern void omap2xxx_prm_dpll_reset(void);
+
 extern int __init prm2xxx_init(void);
 extern int __exit prm2xxx_exit(void);