remoteproc/omap: fix randconfig unmet direct dependencies
OMAP_REMOTEPROC selects REMOTEPROC and RPMSG, both of which depend
on EXPERIMENTAL, so let's have OMAP_REMOTEPROC depend on EXPERIMENTAL
too, in order to avoid the below randconfig warnings.
warning: (OMAP_REMOTEPROC) selects REMOTEPROC which has unmet direct dependencies (EXPERIMENTAL)
warning: (OMAP_REMOTEPROC) selects RPMSG which has unmet direct dependencies (EXPERIMENTAL)