net: wireless: bcmdhd: Update to version 1.88.21

Change-Id: Id7564b294cd999431684ff74b0ca1ae279432372
Source: https://android.googlesource.com/kernel/common/+/android-3.4
Merge pull request #14 from crpalmer/cm-10.1-chad-bcmdhd

net: wireless: bcmdhd: Update to version 1.88.21