ARM: l2c: omap2: remove explicit SMI calls to enable L2 cache

Now that OMAP2 uses the write_sec method, we don't need to enable the L2
cache in OMAP2 specific code; this can be done via the normal mechanisms
in the L2C code.  Remove the OMAP2 specific code.

Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>