bnxt_en: Refactor some basic ring setup and adjustment logic

bnxt_en: Refactor some basic ring setup and adjustment logic

Refactor out the basic code that trims the default rings, sets up and
adjusts XDP TX rings and CP rings.  There is no change in behavior.
This is to prepare for the next bug fix patch.

Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Reviewed-by: Andy Gospodarek <andrew.gospodarek@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20260331065138.948205-2-michael.chan@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>