ARM: OMAP2+: create dsp device only on OMAP3 SoCs

The DSP platform device for TI DSP/Bridge is currently
created unconditionally whenever CONFIG_TIDSPBRIDGE is
enabled. This device should only be created on OMAP34xx/
OMAP36xx SoCs, and not for other OMAP3 derived SoCs or when
booting multi-arch images on other SoCs. So, add a check for
the SoC family both before creating the device and allocating
the carveout memory for the device.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>