hwspinlock: qcom: Add support for Qualcomm HW Mutex block

Add driver for Qualcomm Hardware Mutex block found in many Qualcomm
SoCs.

Based on initial effort by Kumar Gala <galak@codeaurora.org>

Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Reviewed-by: Andy Gross <agross@codeaurora.org>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>