clk: qcom: clk-regmap: Add additional check for devm_clk_register_regmap

Currently, a clock driver can call the devm_clk_register_regmap
function without the device and regmap pointers populated. This
will lead to a NULL pointer dereference in the clock framework.
Treat this more gracefully and return an error to the client
instead.

Change-Id: I2927e7c0fb19046582dd9bf0ae7e77b6c015a0cf
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>