staging: rtl8723bs: core: Remove an unused variable

Delete local variable "u8 sec_idx" because is declared and set, but never
used.

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20210410150008.5460-4-fmdefrancesco@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>