bnxt_en: Fix Rx CQ consumer index on Thor2 to prevent interrupt storm

[chandrakanth.patil_broadcom.com]

Summary

On Thor2, the Rx Completion Queue consumer index was incorrect, causing
continuous interrupts. Updated the index handling to stop the interrupt storm.

[chandrakanth.patil_broadcom.com]

its been long the patches not reviewed so please review the patch and provide your comments.

[gallatin]

sys/dev/bnxt/bnxt_en/if_bnxt.c

1492

This if-then is just another increment. Eg, you're saying
if cons == 0xffffffff, then saying cons = 0. is exactly the same as saying cons = cons++ because cons++ will wrap back to zero on that increment.

So it would be simpler to skip the if/then and just always increment.