bnxt_en: Increase timeout for HWRM_DBG_COREDUMP_XX commands

Firmware coredump messages take much longer than standard messages,
so increase the timeout accordingly.

Fixes: 6c5657d0

 ("bnxt_en: Add support for ethtool get dump.")
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>