bnxt_en: Disable interrupts when allocating CP rings or NQs.

When calling firmware to allocate a CP ring or NQ, an interrupt associated
with that ring may be generated immediately before the doorbell is even
setup after the firmware call returns.  When servicing the interrupt, the
driver may crash when trying to access the doorbell.

Fix it by disabling interrupt on that vector until the doorbell is
set up.

Fixes: 697197e5 ("bnxt_en: Re-structure doorbells.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>