bnxt_en: Add new flags to setup new page table PTE bits on newer devices.

Newer chips require the PTU_PTE_VALID bit to be set for every page
table entry for context memory and rings.  Additional bits are also
required for page table entries for all rings.  Add a flags field to
bnxt_ring_mem_info struct to specify these additional bits to be used
when setting up the pages tables as needed.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>