clk: qcom: Add qcom_clk_hw_get_name()

The existing clk_hw_get_name() only works after the clock has been
registered with the framework since it relies on hw->core->name and
hw->core is NULL pre-registration. hw->init->name can be used
pre-registration, but this doesn't work post-registration since the
framework sets hw->init to NULL.

Provide qcom_clk_hw_get_name(), which can be called in both pre and
post-registration contexts.

Change-Id: I334e545f5112961b7ab6879daca55c70236338d6
Signed-off-by: Mike Tipton <mdtipton@codeaurora.org>