icnss: Add support of setting MAC address from platform driver

Add support of setting WLAN MAC address from platform driver.
The MAC address will be passed to WLAN driver when WLAN is
turned on.

CRs-Fixed: 1096286
Change-Id: I249222b419dd130241cbc84f4d41709b408941e0
Signed-off-by: Yuanyuan Liu <yuanliu@codeaurora.org>