wilc1000: use strlcpy to avoid 'stringop-truncation' warning

Make use 'strlcpy' instead of 'strncpy' to overcome 'stringop-truncation'
compiler warning.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200710051826.3267-3-ajay.kathat@microchip.com