qcacld-3.0: Rename HDD variable roamRssiDiff

The Linux Coding Style frowns upon mixed-case names so rename HDD
local variable roamRssiDiff to be compliant.

Change-Id: I26858cd00fc9a2efb47b6022d9a7f2083976769e
CRs-Fixed: 2408525
1 file changed