mfd: qcom-spmi-pmic: Add specific compatible strings for Qualcomm's SPMI PMIC's

Some of the PMIC's could have specific regmap configuration
tables in future, so add specific compatible strings for known
PMIC's. Also print runtime detected chip revision information.

Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>