staging: r8188eu: remove bt efuse definitions

This driver does not use bt efuses. Remove global variables and
definitions related to bt efuses.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211113185518.23941-14-martin@kaiser.cx


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