Introduce class to create data partition

[sergioprado]

This class will enable the creation of a data partition in the eMMC for Easy Installer images.

This will make it possible to have a read-write partition for situations where the rootfs is read-only (e.g. when dm-verity is enabled).

A few additional variables can be used to configure this feature:

• TDX_TEZI_DATA_PARTITION_TYPE: data partition filesystem type (ext2, ext3, ext4, fat, ubifs)
• TDX_TEZI_DATA_PARTITION_LABEL: data partition label
• TDX_TEZI_DATA_PARTITION_AUTOMOUNT: configure whether the data partition should be automatically mounted at boot time or not
• TDX_TEZI_DATA_PARTITION_MOUNTPOINT: data partition mount point
• TDX_TEZI_DATA_PARTITION_MOUNT_FLAGS: data partition mount flags (to be added to fstab)

This depends on a feature added to image_type_tezi.bbclass in meta-toradex-bsp-common, already merged upstream:

https://git.toradex.com/cgit/meta-toradex-bsp-common.git/commit/?h=kirkstone-6.x.y&id=bbb39c255936a130c18d4eb9410b9558fe5a137b

Build and runtime tested on Verdin iMX8MP.

[sergioprado]

I assume the defaults on the other variables are okay for most general purposes.

Exactly! But of course it can be changed by the user if needed. I might mention this in the documentation, that I plan to write as soon as this is merged.