net/bnxt: remove EEM system memory support

Remove the memory management scheme for Extended Exact Match
using system memory. Using host memory scheme instead which
was the default anyway.

Fixes: b2da02480cb7 ("net/bnxt: support EEM system memory")

Signed-off-by: Randy Schacher <stuart.schacher@broadcom.com>
Signed-off-by: Ajit Khaparde <ajit.khaparde@broadcom.com>
Reviewed-by: Peter Spreadborough <peter.spreadborough@broadcom.com>
Reviewed-by: Farah Smith <farah.smith@broadcom.com>