net: usb: lan78xx: Add error handling to lan78xx_irq_bus_sync_unlock

Update `lan78xx_irq_bus_sync_unlock` to handle errors in register
read/write operations. If an error occurs, log it and exit the function
appropriately.  This ensures proper handling of failures during IRQ
synchronization.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20241204084142.1152696-10-o.rempel@pengutronix.de


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