ARM: 8258/1: l2c: use l2c_write_sec() for restoring latency and filter regs

All four register for latency and filter settings cannot be written in
non-secure mode and they should go through l2c_write_sec(). More on this
can be found in CoreLink Level 2 Cache Controller L2C-310 Technical
Reference Manual, 3.2. Register summary, table 3.1. This have been checked
the TRM for r3p3, but it should be uniform for all revisions.

Reported-by: Nishanth Menon <nm@ti.com>
Suggested-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Nishanth Menon <nm@ti.com>
Acked-by: Nishanth Menon <nm@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>