cnss: Add pre-allocation feature for CNSS platform driver

Make WCNSS pre-allocation feature code as a module which can be shared
by CNSS and WCNSS platform drivers. It will reserve chunks of memory at
booting time so that WLAN host driver can directly use them in case that
kernel cannot allocate large memory immediately.

Change-Id: I6f532db52a53140632459184d9a0f523f9dccda8
CRs-fixed: 662637
Signed-off-by: Yue Ma <yuem@codeaurora.org>