omap: omap-mcbsp: Fix building after replacement

Fix building omap-mcbsp after replacing ARCH_OMAP24x0 in
commit 8a9c1aa6a4caa7db1c2fca4b47168af9077e0f95.

>   omap: Start using CONFIG_SOC_OMAP
>
>    We want to have just CONFIG_ARCH_OMAP2, 3 and 4. The rest
>    are nowadays just subcategories of these.
>
>    Search and replace the following:
>
>    ARCH_OMAP2420               SOC_OMAP2420
>    ARCH_OMAP2430               SOC_OMAP2430
>    ARCH_OMAP3430               SOC_OMAP3430

Signed-off-by: Thomas Weber <weber@corscience.de>
Acked-by: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>