OMAP4: fix temporary hacks that break multi-omap PM

When building for multi-omap, and OMAP4 is enabled, CONFIG_ARCH_OMAP4
will be true and prevent included code from building/running for
OMAP2/3 as well.

This problem exists in io.c where some hwmod/PM/SDRC init code is
prevented from running even on OMAP2/3 when OMAP4 is included in a
multi-OMAP build.

A quick glance suggests that this #ifndef is no longer needed in most
of the cases.  In the remaining cases, the function is wrapped with
"if (cpu_is_omap24xx() || cpu_is_omap34xx())" which will be optimized
out for OMAP4-only builds.

Note that this is only a short-term fix.  Longer-term, OMAP4
needs to create init functions for SDRC and hwmod late-init.

Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>