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>

drivers/platform/chrome/cros_ec_spi.c

@@ -104,13 +104,7 @@ static void debug_packet(struct device *dev, const char *name, u8 *ptr,
 			 int len)
 {
 #ifdef DEBUG
-	int i;
-
-	dev_dbg(dev, "%s: ", name);
-	for (i = 0; i < len; i++)
-		pr_cont(" %02x", ptr[i]);
-
-	pr_cont("\n");
+	dev_dbg(dev, "%s: %*ph\n", name, len, ptr);
 #endif
 }