west: linkserver: fix erase error

- Fixes linkserver runner "west flash --erase" error:
  ERRMSG: Exception: Device query can have at most 2 parts (3 found)
- There is no need to specify the core with
  the flash erase command line.

Signed-off-by: Andrej Butok <andrey.butok@nxp.com>
1 file changed