configs: remove support of MTDIDS_DEFAULT/MTDPARTS_DEFAULT

Complete the migration of MTDPARTS_DEFAULT / MTDIDS_DEFAULT in Kconfig;
this patch removes the support of MTDIDS_DEFAULT / MTDPARTS_DEFAULT
in the configuration files (include/configs/*.h).

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>