samples/logger-hook: fix usage of ring buffer

- Ring buffers provide no concurrency control. Since the ring buffer
is being installed as the system log hook, multiple contexts may try
to write to it simultaneously. Lock interrupts to prevent corruption
of the ring buffer.

- NULL pointers were being passed into sys_ring_buf_get() for the
'type' and 'value' parameters, causing undesirable behavior when they
are dereferenced.

- The 'size32' parameter of sys_ring_buf_put() was being passed the
number of bytes, not the number of 32-bit words.

- The 'size32' parameter of sys_ring_buf_get() was not bring correctly
initialized the size of the destination buffer in terms of 32-bit
words. This has been fixed. There is no longer a need to query the
API twice.

Issue: ZEP-1789
Change-Id: I96f9cc74f3711297727b4c5114b6c93510f4a8c1
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>