s390/zcrypt: utilize dev_set_name() ability to use a formatted string

s390/zcrypt: utilize dev_set_name() ability to use a formatted string

With the dev_set_name() prototype it's not obvious that it takes
a formatted string as a parameter. Use its facility instead of
duplicating the same with strncpy()/snprintf() calls.

With this, also prevent return error code to be shadowed.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230831110000.24279-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>