arm: imx: imx8mm: clock: make debug output more descriptive

Clock initialization functionality has ambitious debug messages, which are
printed out when failures are triggered during execution:
- Separate frequency table lookup functions have the the same output that
  makes it impossible to understand which function failed and produced the
  output
- PLL decoding routine has a generic debug statement printed, which does
  not state the actual value failed to be found

Extend the output for both cases with prefixing table lookup functions
output with function name, and report the failed value in PLL decoding
routine.

Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: "NXP i.MX U-Boot Team" <uboot-imx@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Ye Li <ye.li@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>