bnxt_en: Use a larger RSS indirection table on P5_PLUS chips

bnxt_en: Use a larger RSS indirection table on P5_PLUS chips

The driver currently uses a chip supported RSS indirection table size
just big enough to cover the number of RX rings.  Each table with 64
entries requires one HW RSS context.  The HW supported table sizes are
64, 128, 256, and 512 entries.  Using the smallest table size can cause
unbalanced RSS packet distributions.  For example, if the number of
rings is 48, the table size using existing logic will be 64.  32 rings
will have a weight of 1 and 16 rings will have a weight of 2 when
set to default even distribution.  This represents a 100% difference in
weights between some of the rings.

Newer FW has increased the RSS indirection table resource.  When the
increased resource is detected, use the largest RSS indirection table
size (512 entries) supported by the chip.  Using the same example
above, the weights of the 48 rings will be either 10 or 11 when set to
default even distribution.  The weight difference is only 10%.

If there are thousands of VFs, there is a possiblity that we may not
be able to allocate this larger RSS indirection table from the FW, so
we add a check to fall back to the legacy scheme.

Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20260108183521.215610-6-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>