wifi: iwlwifi: Remove support for rx OMI bandwidth reduction

This feature turns out to have an issue: it can take up to 8 seconds to
detect high throughput scenarios and to leave RX OMI bandwidth
reduction. This leads to throughput degradation.
Until the issues are fixed, remove the RX OMI implementation.

Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250723094230.a9ccfe210516.Ic87bc7709a6761f593e88f1488a41442c68c1686@changeid