cpu: microblaze: add error handling in microblaze_cpu_get_desc()

cpu: microblaze: add error handling in microblaze_cpu_get_desc()

Check snprintf() return value for errors.

Make microblaze_cpu_get_desc() directly return snprintf() error code if
ret < 0. Otherwise, if the return value is greater than or equal to size,
the resulting string is truncated, so return -ENOSPC.

Fixes: 816226d27e ("cpu: add CPU driver for microblaze")
Signed-off-by: Ovidiu Panait <ovpanait@gmail.com>
Link: https://lore.kernel.org/r/20220829170205.1274484-2-ovpanait@gmail.com
Signed-off-by: Michal Simek <michal.simek@amd.com>