Replaced PULP_HWLP by PULP_XPULP and guarded PULP extensions

Created by: Silabs-ArjanB

The PULP_HWLP parameter has been replaced by PULP_XPULP (default 1).

PULP_XPULP guards the following:

• All custom instructions except p.elw (which is guarded by PULP_CLUSTER)
• All custom CSRs:
  • lpstart0
  • lpend0
  • lpcount0
  • lpstart1
  • lpend1
  • lpcount1
  • privlv
  • uhartid
  • fprec

Note: Although hardware loop is now default enabled, it is not (yet) supported in the current RTL (awaiting fetch stage updates).

Signed-off-by: Arjan Bink Arjan.Bink@silabs.com