iwlwifi: mvm: BT Coex - fix the ACK / CTS kill mask

According to new requirements, the ACK / CTS kill mask is
not related to reduced TX power anymore. This allows to
remove the code that tracked reduced TX power enablement
across different interfaces.
The ACK / CTS kill mask is now fetch from a table. It
depends on the Activity grading (activity from BT) and on
the Look Up Table (LUT) type.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>