hwspinlock: qcom: Allow mmio usage in addition to syscon

In modern Qualcomm platforms the mutex region of the TCSR is forked off
into its own block, all with a offset of 0 and stride of 4096, and in
some of these platforms no other registers in this region is accessed
from Linux.

So add support for directly memory mapping this register space, to avoid
the need to represent this block using a syscon.

Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Reviewed-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200622075956.171058-4-bjorn.andersson@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>