msm: npu: Allocate ipc buffer during driver initialization

This change is to allocate ipc buffer during driver initialization
to improve the performance. It also increases the ipc buffer size
to the same as ipc queue size to avoid buffer overflow issue.

Change-Id: I41ebaf6830d2578aa5f5bc21304bf5616de04445
Signed-off-by: Jilai Wang <jilaiw@codeaurora.org>