unified: Eliminate k_mem_pool_t typedef

Replaces it with a pointer as there is no need for an opaque memory
pool type.

Jira: ZEP-916
Change-Id: I5493eed25c9c34e1b850dc3b20699864edb22d28
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>
3 files changed