clk: zynqmp: Fix invalid clock name queries

clk: zynqmp: Fix invalid clock name queries

The clock driver makes EEMI call to get the name of invalid clk
when executing versal_get_clock_info() function. This results in
error messages.
Added check for validating clock before saving clock attribute and
calling zynqmp_pm_clock_get_name() in versal_get_clock_info() function.

Signed-off-by: Rajan Vaja <rajan.vaja@xilinx.com>
Signed-off-by: Tejas Patel <tejas.patel@xilinx.com>
Signed-off-by: Jolly Shah <jolly.shah@xilinx.com>
Link: https://lkml.kernel.org/r/1583185843-20707-4-git-send-email-jolly.shah@xilinx.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>