bnxt_en: Fix error handling path in bnxt_init_chip()

WARN_ON() is triggered in __flush_work() if bnxt_init_chip() fails
because we call cancel_work_sync() on dim work that has not been
initialized.

WARNING: CPU: 37 PID: 5223 at kernel/workqueue.c:4201 __flush_work.isra.0+0x212/0x230

The driver relies on the BNXT_STATE_NAPI_DISABLED bit to check if dim
work has already been cancelled.  But in the bnxt_open() path,
BNXT_STATE_NAPI_DISABLED is not set and this causes the error
path to think that it needs to cancel the uninitalized dim work.
Fix it by setting BNXT_STATE_NAPI_DISABLED during initialization.
The bit will be cleared when we enable NAPI and initialize dim work.

Fixes: 40452969 ("bnxt_en: Fix DIM shutdown")
Suggested-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Signed-off-by: Shravya KN <shravya.k-n@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>