LinuxKPI: add dummy hash.h and kernel_connect()

Add crypto/hash.h and a dummy kernel_connect() needed to compile
the ath11k wireless driver. While I hope we will not actually need
the hash.h fallbacks, kernel_connect() we will have to deal with once
we sort out more QMI bits.

(cherry picked from commit d544b53cb0b6bc25f2ba078bd9c07e611095bf29)