ARM: imx: Deduplicate Data Modul i.MX8M eDM SBC defconfigs

ARM: imx: Deduplicate Data Modul i.MX8M eDM SBC defconfigs

Deduplicate defconfigs for all Data Modul i.MX8M eDM SBC systems by factoring
out the common parts into generic imx8m_data_modul.config and including
those using the #include <configs/...> preprocessor macro in the current
set of board specific defconfigs. The preprocessor macro is applicable
to defconfigs as well.

This introduces no functional change, the resulting .config is almost
identical for all Data Modul i.MX8M eDM SBC systems, except for slight
alignment in DEBUG_UART and SYS_PBSIZE.

Signed-off-by: Marek Vasut <marex@denx.de>