msm: kgsl: Use the correct spin_lock variant for HFI

The msglock is used both in a user context and in
a tasklet. In this case, the correct way to protect
the critical sections and prevent deadlocks is to
use spin_lock_bh() and spin_unlock_bh(). Change the
HFI code to use these functions.

Change-Id: I8ebb075fc48073858a3ce7eb36d57641c19eba9a
Signed-off-by: Kyle Piefer <kpiefer@codeaurora.org>