platform/chrome: cros_ec_spi: Use %*ph for printing hexdump of a small buffer

The kernel already has a helper to print a hexdump of a small
buffer via pointer extension. Use that instead of open coded
variant.

In long term it helps to kill pr_cont() or at least narrow down
its use.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230612212336.4961-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>