Move the OMAP4 global software reset function to the OMAP4-specific
prm44xx.c file, where it belongs.  Part of the long-term process of
moving all of the direct PRCM register writes into lower-layer code.

Also add OCP barriers on OMAP2/3/4 to reduce the chance that the MPU
will continue executing while the system is supposed to be resetting
itself.
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Tested-by: NSantosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: NRajendra Nayak <rnayak@ti.com>