netdev: broadcom: propagate error code

Function bnxt_hwrm_stat_ctx_alloc() always returns 0, even if the call
to _hwrm_send_message() fails. It may be better to propagate the errors
to the caller of bnxt_hwrm_stat_ctx_alloc().

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188661



Signed-off-by: Pan Bian <bianpan2016@163.com>
Acked-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>