Remove erasing from ram store

The RAM block store is a RAM-based device, so it should not assume
that storage must be erased before writing, unlike flash memory.
This change removes the unnecessary check, improving efficiency
and extending the expected lifetime of the storage device.
Additionally, the relevant tests have been updated accordingly.

Change-Id: I3156002cac7654e8b301aea3fdd56d0d533357ba
Signed-off-by: Gabor Toth <gabor.toth2@arm.com>
3 files changed