net/bnxt: support runtime EM selection

net/bnxt: support runtime EM selection

This patch adds support to select internal Exact Match vs
External Exact Match support while loading the PMD.
- Added new mem type conditional opcode for internal/external
- Adapted the flowdb resource counts based on selected mode
- Template changes to use the new opcode
- The decision for internal/external EM support is based on the
  devargs parameter max_num_kflows.  If this is set, external EM
  is used.

Signed-off-by: Mike Baucom <michael.baucom@broadcom.com>
Reviewed-by: Kishore Padmanabha <kishore.padmanabha@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>