sr9800: Add check for usbnet_get_endpoints

Add check for usbnet_get_endpoints() and return the error if it fails
in order to transfer the error.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Reviewed-by: Simon Horman <horms@kernel.org>
Fixes: 19a38d8e ("USB2NET : SR9800 : One chip USB2.0 USB2NET SR9800 Device Driver Support")
Link: https://lore.kernel.org/r/20240305075927.261284-1-nichen@iscas.ac.cn


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