Multi_PollingProc: use slot variable
Multi_PollingProc: use slot variable

Use the slot variable instead of calculating the number every time.

This also fixes the warning from clang:

ccid_usb.c:1521:11: warning: variable 'slot' set but not used [-Wunused-but-set-variable]

LudovicRousseau/CCID,LudovicRousseau/CCID,LudovicRousseau/CCID