Squashed commit of the following:
Change all remaining occurrences of SAMDL to SAMD2L2.
configs/: Change all remaining occurrences of SAMDL to SAMD2L2
configs/: Change all occurrences of CONFIG_SAMDL_* to CONFIG_SAMD2L2_*
arch/arm/src and include: Rename all directories from samdl to samd2l2. Change all configuration variable names and other usage from SAMDL to SAMD2L2.