crypto: hifn_795x - replace simple_strtoul with kstrtouint

crypto: hifn_795x - replace simple_strtoul with kstrtouint

Replace simple_strtoul() with the recommended kstrtouint() for parsing
the 'hifn_pll_ref=' module parameter. Unlike simple_strtoul(), which
returns an unsigned long, kstrtouint() converts the string directly to
an unsigned integer and avoids implicit casting.

Check the return value of kstrtouint() and fall back to 66 MHz if
parsing fails. This adds error handling while preserving existing
behavior for valid values, and removes use of the deprecated
simple_strtoul() helper.

Add a space in the log message to correctly format "66 MHz" while we're
at it.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>