ath6kl: fix size_t related warnings

My earlier debug log additions added these warnings when compiling 64 bit
kernels:

ath6kl/init.c:962: warning: format '%d' expects type 'int',
  but argument 3 has type 'size_t'
ath6kl/init.c:975: warning: format '%d' expects type 'int',
  but argument 3 has type 'size_t'
ath6kl/init.c:988: warning: format '%d' expects type 'int',
  but argument 3 has type 'size_t'
ath6kl/init.c:1009: warning: format '%d' expects type 'int',
  but argument 3 has type 'size_t'
ath6kl/init.c:1192: warning: format '%d' expects type 'int',
  but argument 4 has type 'size_t'
ath6kl/init.c:1236: warning: format '%d' expects type 'int',
  but argument 4 has type 'size_t'
ath6kl/init.c:1267: warning: format '%d' expects type 'int',
  but argument 4 has type 'size_t'

Reported-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>