[DEVMEM2] update devmem2 to latest version
Import devmem2_2.0.bb from meta-oe: https://git.openembedded.org/meta-openembedded/tree/meta-oe/recipes-support/devmem2/devmem2_2.0.bb?h=master
The new version has two advantages:
- uses fixed-width integer types (uint32_t, uint64_t) and strict alignment for memory operations, and this prevents a memory bus error when trying to read "unaligned" registers on e.g. rk3568 and rk3399
- supports the l type (64 bits)