iwlwifi: pcie: implement set_pnvm op

Implement the set_pnvm op to store the PNVM settings to the context
info and the corresponding code to free the DRAM block when the
context is freed.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20201008181047.85847cfb0972.I202d90e99779f722df14b2d4102d3e466343a6f6@changeid