mmc: omap_hsmmc: use the generic config for omap2plus devices

mmc: omap_hsmmc: use the generic config for omap2plus devices

OMAP's hs_mmc driver is used for MMC controller operation on many
omap2plus SoCs (OMAP2430, OMAP3, 4, 5 and AM335x).

Considering that the device tree entries are already present for these,
allow the driver to be built using the config ARCH_OMAP2PLUS rather
than individually adding a config for each SoC to enable the
support.

Use COMPILE_TEST to enable the build for other platforms.

Signed-off-by: Amarinder Bindra <[email protected]>
Cc: Ezequiel Garcia <[email protected]>
Cc: Nishanth Menon <[email protected]>
Acked-by: Felipe Balbi <[email protected]>
Acked-by: Balaji T K <[email protected]>
Signed-off-by: Chris Ball <[email protected]>