qcacld-3.0: Refactor WE_SET_11N_RATE processing

One of the HDD functions with the highest cyclomatic complexity is
__iw_setint_getnone(). The handing of WE_SET_11N_RATE has a complexity
greater than 1, so refactor that logic into a separate function to
help reduce the complexity of __iw_setint_getnone().

Change-Id: Iea2ee6bc53a56bb92497d42ac057e6663bc07097
CRs-Fixed: 2340145
1 file changed