octeontx2-pf: check negative error code in otx2_open()

otx2_rxtx_enable() return negative error code such as -EIO,
check -EIO rather than EIO to fix this problem.

Fixes: c9262522

 ("octeontx2-pf: Disable packet I/O for graceful exit")
Signed-off-by: Su Hui <suhui@nfschina.com>
Reviewed-by: Subbaraya Sundeep <sbhatta@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://lore.kernel.org/r/20240328020620.4054692-1-suhui@nfschina.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>