qcacmn: Properly export wlan_cfg API

Currently some of the public functions in wlan_cfg.c do not have their
prototypes exposed in a header file. This causes compilation warnings
when the driver is compiled with the -Wmissing-prototypes switch.  Fix
these issues by adding the prototypes to wlan_cfg.h.

Change-Id: I914b811fdd8d48c9570bd240f0fdc8192b21c2e8
CRs-Fixed: 1108113
1 file changed