wlan: Get Mac addr from platform driver

Read the MAC address from the platform driver preferrably and
fall back to the option of auto generating the same, if the
MAC read is invalid.

Change-Id: I8a7529bdf7f0d146a2c128a697ebe8c7c374f40a
CRs-Fixed: 583465
Merge branch 'cm-11.0' into kk_mkt