bnxt_en: Reset rings if ring reservation fails during open()

If ring counts are not reset when ring reservation fails,
bnxt_init_dflt_ring_mode() will not be called again to reinitialise
IRQs when open() is called and results in system crash as napi will
also be not initialised. This patch fixes it by resetting the ring
counts.

Fixes: 47558acd

 ("bnxt_en: Reserve rings at driver open if none was reserved at probe time.")
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>