bnxt_en: Refactor bnxt_need_reserve_rings()

bnxt_en: Refactor bnxt_need_reserve_rings()

bnxt_need_reserve_rings() checks 6 ring resources against the reserved
values to determine if a new reservation is needed.  Factor out the code
to collect the total resources into a new helper function
bnxt_get_total_resources() to make the code cleaner and easier to read.
Instead of individual scalar variables, use the struct bnxt_hw_rings to
hold all the ring resources.  Using the struct, hwr.cp replaces the nq
variable and the chip specific hwr.cp_p5 replaces cp on newer chips.

There is no change in behavior.  This will make it easier to check the
RSS context resource in the next patch.

Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Reviewed-by: Joe Damato <joe@dama.to>
Link: https://patch.msgid.link/20260207235118.1987301-2-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>