qcacmn: Fix header include bug
This is a qcacld-2.0 to qcacld-3.0 propagation.
In file ar9888def.h error: '_AR9888DEF_H_' is used as a header guard here,
followed by #define of a different macro [-Werror,-Wheader-guard]
ar9888def.h: note: 'AR9888__AR9888DEF_H_' is defined here; did you mean '_AR9888DEF_H_'?
Fix the header file include guard properly.
Change-Id: Ic05a829eadbf974598370c494a5cff10201ec600
CRs-Fixed: 1091052